Michael P Lesser

Interests

Research

CCDs, CMOS imagers, optical and UV sensor characterization, astronomical instrumentation

Courses

Scholarly Contributions

Chapters

• Lesser, M. P. (2019). Charge-coupled device (CCD) image sensors (2nd edition). In High Performance Silicon Imaging.
  More info

  Second edition
• Lesser, M. P. (2014). Charge Coupled Device (CCD) Image Sensors. In High performance silicon imaging : fundamentals and applications CMOS and CCD sensors(pp 78-97). Cambridge: Woodhead Publishing.
• Lesser, M. P. (2004). Very Large Format Back Illuminated CCDs. In Scientific Detectors for Astronomy. doi:10.1007/978-1-4020-2527-3_15
• Lesser, M. P., Lesser, M. P., & Ouellette, D. (2004). Fully Buttable Imagers. In Scientific Detectors for Astronomy, 2004. Springer, Dordrecht. doi:10.1007/1-4020-2527-0_74
  More info

  A new post-fabrication technique has been developed which allows charge coupled device wafers to be hybridized and then processed for backside illumination. This allows the creation of a fully buttable imager in which the electrical I/O from the device frontside is brought under the device rather than to its edge. This 3-D packaging allows extremely close spacing of imagers in a focal plane mosaic. It also allows standardized processing for wafers of the same size, which may lead to lower cost of back-illuminated detectors.
• Lesser, M. P., Lesser, M. P., & Parthasarathy, M. (2004). AzCam: A Windows-Based CCD/CMOS Client/Server Data Acquisition System. In Scientific Detectors for Astronomy. Astrophysics and Space Science Library. Springer, Dordrecht. doi:10.1007/1-4020-2527-0_57
  More info

  AzCam is a software package developed to utilize a common architecture for the characterization of CCD and CMOS imagers in both laboratory and astronomical observatory environments. It follows a standard client/server model in which the server runs on a PC under the Microsoft Windows operating system to allow easy integration with the many CMOS imager cameras.
• Denton, M. B., Lesser, M. P., Lesser, M. P., Bredthauer, R., & Denton, M. B. (2000). Development of a back-illuminated 4096×4096 15-micron pixel scientific CCD. In Further Developments in Scientific Optical Imaging. doi:10.1039/9781847550958-00111
• Miley, G. K., Macchetto, F. D., Deharveng, J., Fosbury, R. A., Kudritzki, R., Paresce, F., Cordova, F. A., Crocker, J., Huchra, J. P., Illingworth, G. D., Lesser, M. P., & Brown, R. H. (1994). An Advanced Camera for the Hubble Space Telescope. In Frontiers of Space And Ground-Based Astronomy. Springer, Dordrecht. doi:10.1007/978-94-011-0794-5_53
  More info

  This paper describes a proposal for a new camera for the HST, to be launched in 1999. It will offer an order of magnitude increase in performance compared with existing cameras.

Journals/Publications

• Dey, A., Schlegel, D. J., Lang, D., Blum, R., Burleigh, K., Fan, X., Findlay, J. R., Finkbeiner, D., Herrera, D., Juneau, S., Landriau, M., Levi, M., McGreer, I., Meisner, A., Myers, A. D., Moustakas, J., Nugent, P., Patej, A., Schlafly, E. F., , Walker, A. R., et al. (2019). Overview of the DESI Legacy Imaging Surveys. The Astronomical Journal.
• Lesser, M. P. (2019). The Third Data Release of the Beijing-Arizona Sky Survey. The Astrophysical Journal Supplement Series.
  More info

  The Beijing-Arizona Sky Survey (BASS) is a wide and deep imaging survey tocover a 5400 deg$^2$ area in the Northern Galactic Cap with the 2.3m Boktelescope using two filters ($g$ and $r$ bands). The Mosaic $z$-band LegacySurvey (MzLS) covers the same area in $z$ band with the 4m Mayall telescope.These two surveys will be used for spectroscopic targeting of the Dark EnergySpectroscopic Instrument (DESI). The BASS survey observations were completed in2019 March. This paper describes the third data release (DR3) of BASS, whichcontains the photometric data from all BASS and MzLS observations between 2015January and 2019 March. The median astrometric precision relative to {\it Gaia}positions is about 17 mas and the median photometric offset relative to thePanSTARRS1 photometry is within 5 mmag. The median $5\sigma$ AB magnitudedepths for point sources are 24.2, 23.6, and 23.0 mag for $g$, $r$, and $z$bands, respectively. The photometric depth within the survey area is highlyhomogeneous, with the difference between the 20\% and 80\% depth less than 0.3mag. The DR3 data, including raw data, calibrated single-epoch images,single-epoch photometric catalogs, stacked images, and co-added photometriccatalogs, are publicly accessible at\url{http://batc.bao.ac.cn/BASS/doku.php?id=datarelease:home}.[Journal_ref: ]
• Zou, H. u., Zhang, T., Zhou, Z., Peng, X., Nie, J., Zhou, X. u., Fan, X., Jiang, L., McGreer, I., Dey, A., Fan, D., Findlay, J. R., Gao, J., Gu, Y., Guo, Y., He, B., Jin, J., Kong, X. u., Lang, D., , Lei, F., et al. (2018). The Second Data Release of the Beijing─Arizona Sky Survey. The Astrophysical Journal Supplement Series, 237, 37.
• Lesser, M. P. (2017). The Galactic extinction and reddening from the South Galactic Cap U-band Sky Survey: u band galaxy number counts and $u-r$ color distribution. The Astronomical Journal.
  More info

  We study the integral Galactic extinction and reddening based on the galaxycatalog of the South Galactic Cap U-band Sky Survey (SCUSS), where $u$ bandgalaxy number counts and $u-r$ color distribution are used to derive theGalactic extinction and reddening respectively. We compare these independentstatistical measurements with the reddening map of \citet{Schlegel1998}(SFD)and find that both the extinction and reddening from the number counts andcolor distribution are in good agreement with the SFD results at low extinctionregions ($E(B-V)^{SFD}0.12$ mag), the SFD map overestimates the Galactic reddeningsystematically, which can be approximated by a linear relation $\Delta E(B-V)=0.43[E(B-V)^{SFD}-0.12$]. By combing the results of galaxy number counts andcolor distribution together, we find that the shape of the Galactic extinctioncurve is in good agreement with the standard $R_V=3.1$ extinction law of\cite{ODonnell1994}.[Journal_ref: ]
• Lesser, M., & Ouellette, D. (2017). Results from STA/ITL fully depleted CCDs for LSST. Journal of Instrumentation, 12, C03080.
• Li, L., Shen, S., Hou, J., Yuan, F., Zhong, J., Zou, H., Zhou, X., Jiang, Z., Peng, X., Fan, D., Fan, X., Fan, Z., He, B., Jing, Y., Lesser, M., Li, C., Ma, J., Nie, J., Wang, J., , Wu, Z., et al. (2017). Galactic Extinction and Reddening from the South Galactic Cap u-band Sky Survey: u-band Galaxy Number Counts and u - r Color Distribution. AJ, 153, 88.
• Zhou, Z., Zhou, X., Wu, H., Fan, X., Fan, Z., Jiang, Z., Jing, Y., Li, C., Lesser, M., Jiang, L., Ma, J., Nie, J., Shen, S., Wang, J., Wu, Z., Zhang, T., & Zou, H. (2017). Scuss u-Band Emission as a Star-Formation-Rate Indicator. ApJ, 835, 70.
• Zou, H., Zhang, T., Zhou, Z., Nie, J., Peng, X., Zhou, X., Jiang, L., Cai, Z., Dey, A., Fan, X., Fan, D., Guo, Y., He, B., Jiang, Z., Lang, D., Lesser, M., Li, Z., Ma, J., Mao, S., , McGreer, I., et al. (2017). The First Data Release of the Beijing-Arizona Sky Survey. AJ, 153, 276.
• Zou, H., Zhang, T., Zhou, Z., Peng, X., Nie, J., Zhou, X., Fan, X., Jiang, L., McGreer, I., Dey, A., Fan, D., Findlay, J., Gao, J., Gu, Y., Guo, Y., He, B., Jin, J., Kong, X., Lang, D., , Lei, F., et al. (2017). The Second Data Release of the Beijing-Arizona Sky Survey. ArXiv e-prints.
• Zou, H., Zhou, X., Fan, X., Zhang, T., Zhou, Z., Nie, J., Peng, X., McGreer, I., Jiang, L., Dey, A., Fan, D., He, B., Jiang, Z., Lang, D., Lesser, M., Ma, J., Mao, S., Schlegel, D., & Wang, J. (2017). Project Overview of the Beijing-Arizona Sky Survey. PASP, 129(6), 064101.
• , D. C., , A. A., , J. A., , S. A., , S. A., , L. E., , C. A., , J. A., , S. B., , C. B., , O. B., , C. B., , L. B., , C. B., , T. C., , E. F., , J. L., , R. B., , F. B., , , C. B., et al. (2016). The DESI Experiment Part I: Science,Targeting, and Survey Design.
  More info

  DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based darkenergy experiment that will study baryon acoustic oscillations (BAO) and thegrowth of structure through redshift-space distortions with a wide-area galaxyand quasar redshift survey. To trace the underlying dark matter distribution,spectroscopic targets will be selected in four classes from imaging data. Wewill measure luminous red galaxies up to $z=1.0$. To probe the Universe out toeven higher redshift, DESI will target bright [O II] emission line galaxies upto $z=1.7$. Quasars will be targeted both as direct tracers of the underlyingdark matter distribution and, at higher redshifts ($ 2.1 < z < 3.5$), for theLy-$\alpha$ forest absorption features in their spectra, which will be used totrace the distribution of neutral hydrogen. When moonlight prevents efficientobservations of the faint targets of the baseline survey, DESI will conduct amagnitude-limited Bright Galaxy Survey comprising approximately 10 milliongalaxies with a median $z\approx 0.2$. In total, more than 30 million galaxyand quasar redshifts will be obtained to measure the BAO feature and determinethe matter power spectrum, including redshift space distortions.[Journal_ref: ]
• , D. C., , A. A., , J. A., , S. A., , S. A., , L. E., , C. A., , J. A., , S. B., , C. B., , O. B., , C. B., , L. B., , C. B., , T. C., , E. F., , J. L., , R. B., , F. B., , , C. B., et al. (2016). The DESI Experiment Part II: Instrument Design.
  More info

  DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based darkenergy experiment that will study baryon acoustic oscillations and the growthof structure through redshift-space distortions with a wide-area galaxy andquasar redshift survey. The DESI instrument is a robotically-actuated,fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra overa wavelength range from 360 nm to 980 nm. The fibers feed ten three-armspectrographs with resolution $R= \lambda/\Delta\lambda$ between 2000 and 5500,depending on wavelength. The DESI instrument will be used to conduct afive-year survey designed to cover 14,000 deg$^2$. This powerful instrumentwill be installed at prime focus on the 4-m Mayall telescope in Kitt Peak,Arizona, along with a new optical corrector, which will provide a three-degreediameter field of view. The DESI collaboration will also deliver aspectroscopic pipeline and data management system to reduce and archive alldata for eventual public use.[Journal_ref: ]
• Lesser, M. P. (2016). South Galactic Cap u-band Sky Survey (SCUSS): Data Release. AJ, 151(2), 37.
  More info

  The SCUSS is a deep $u$-band imaging survey in the south Galactic cap usingthe 2.3m Bok telescope. The survey observations were completed in the end of2013, covering an area of about 5000 square degrees. We release the data in theregion with an area of about 4000 deg$^2$ that is mostly covered by the Sloandigital sky survey. The data products contain calibrated single-epoch images,stacked images, photometric catalogs, and a catalog of star proper motionsderived by Peng et al, 2015. The median seeing and magnitude limit ($5\sigma$)are about 2".0 and 23.2 mag, respectively. There are about 8 million objectshaving measurements of absolute proper motions. All the data and relateddocumentations can be accessed through the SCUSS data release website of\url{http://batc.bao.ac.cn/Uband/data.html}.[Journal_ref: ]
• Lesser, M. P. (2016). South Galactic Cap u-band Sky Survey (SCUSS): Project Overview. Research in Astronomy and Astrophysics, 16, 69.
• Lesser, M. P. (2016). The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: selecting emission line galaxies using the Fisher discriminant. A&A, 585, 50R.
  More info

  We present a new selection technique of producing spectroscopic targetcatalogues for massive spectroscopic surveys for cosmology. This work wasconducted in the context of the extended Baryon Oscillation SpectroscopicSurvey (eBOSS), which will use ~200 000 emission line galaxies (ELGs) at0.6
• Lesser, M., Zou, H., Zhou, Z., Zhou, X., Zhang, T., Wu, Z., Wang, J., Shen, S., Peng, X., Nie, J., Ma, J., Li, C., Lesser, M., Jing, Y., Jiang, Z., He, B., Fan, Z., Fan, X., & Fan, D. (2016). SOUTH GALACTIC CAP U -BAND SKY SURVEY (SCUSS): DATA RELEASE. The Astronomical Journal, 151(2), 37. doi:10.3847/0004-6256/151/2/37
  More info

  The South Galactic Cap u-band Sky Survey (SCUSS) is a deep u-band imaging survey in the south Galactic cap using the 2.3 m Bok telescope. The survey observations were completed at the end of 2013, covering an area of about 5000 square degrees. We release the data in the region with an area of about 4000 deg2 that is mostly covered by the Sloan digital sky survey. The data products contain calibrated single-epoch images, stacked images, photometric catalogs, and a catalog of star proper motions derived by Peng et al. The median seeing and magnitude limit (5σ) are about 20 and 23.2 mag, respectively. There are about 8 million objects having measurements of absolute proper motions. All the data and related documentations can be accessed through the SCUSS data release website http://batc.bao.ac.cn/Uband/data.html.
• Comparat, J., Richard, J., Kneib, J., Ilbert, O., Gonzalez-Perez, V., Tresse, L., Zoubian, J., Arnouts, S., Bacon, R., Brownstein, J. R., Baugh, C., Delubac, T., Ealet, A., Escoffier, S., Ge, J., Jullo, E., Lacey, C., Ross, N. P., Schlegel, D., , Schneider, D. P., et al. (2014). The 0.1ltzlt1.65 evolution of the bright end of the [OII] luminosity function. ArXiv e-prints.
• Zhou, X., Wang, J. L., Nie, J. D., Lesser, M., Zou, H., Zhou, Z. M., Zhou, X., Zhang, T. M., Wu, Z. Y., Wang, J. L., Smith, M. C., Shen, S. Y., Nie, J. D., Ma, J., Lesser, M., Koposov, S. E., Jing, Y. P., Jiang, Z. J., Irwin, M. J., , Fan, Z., et al. (2015). AN EXTENDED VIEW OF THE PISCES OVERDENSITY FROM THE SCUSS SURVEY. The Astrophysical Journal, 810(2), 153. doi:10.1088/0004-637x/810/2/153
  More info

  The South Galactic Cap u-band Sky Survey (SCUSS) is a u-band photometric survey covering about 4000 square degrees of the South Galactic Cap, reaching depths of up to 23 mag. By extending around 1.5 mag deeper than the Sloan Digital Sky Survey (SDSS) single-epoch u data, SCUSS is able to probe a much larger volume of the outer halo, i.e., with SCUSS data blue horizontal branch (BHB) stars can trace the outer halo of the Milky Way as far as 100-150 kpc. Utilizing this advantage we combine the SCUSS u-band with the SDSS DR9 gri photometric bands to identify BHB stars and explore halo substructures. We confirm the existence of the Pisces overdensity, which is a structure in the outer halo (at around 80 kpc) that was discovered using RR Lyrae stars. For the first time we are able to determine its spatial extent, finding that it appears to be part of a stream with a clear distance gradient. The stream, which is similar to 5 degrees wide and stretches along similar to 25 degrees, consists of 20-30 BHBs with a total significance of around 6 sigma over the background. Assuming we have detected the entire stream and that the progenitor has fully disrupted, then the number of BHBs suggests that the original system was similar to a smaller classical or a larger ultra-faint dwarf galaxy. On the other hand, if the progenitor still exists, it can be hunted for by reconstructing its orbit from the distance gradient of the stream. This new picture of the Pisces overdensity sheds new light on the origin of this intriguing system.
• {Comparat}, J., {Richard}, J., {Kneib}, J., {Ilbert}, O., {Gonzalez-Perez}, V., {Tresse}, L., {Zoubian}, J., {Arnouts}, S., {Brownstein}, J., {Baugh}, C., {Delubac}, T., {Ealet}, A., {Escoffier}, S., {Ge}, J., {Jullo}, E., {Lacey}, C., {Ross}, N., {Schlegel}, D., {Schneider}, D., , {Steele}, O., et al. (2015). The 0.1A&A, 575, A40.
• {Gu}, J., {Du}, C., {Jia}, Y., {Peng}, X., {Wu}, Z., {Jing}, Y., {Ma}, J., {Zhou}, X., {Fan}, X., {Fan}, Z., {Jing}, Y., {Jiang}, Z., {Lesser}, M., {Nie}, J., {Shen}, S., {Wang}, J., {Zou}, H., {Zhang}, T., , Z. (2015). Photometric metallicity calibration with SDSS and SCUSS and its application to distant stars in the south Galactic cap. MNRAS, 452, 3092-3099.
• {Lesser}, M. (2015). A Summary of Charge-Coupled Devices for Astronomy. PASP, 129, 1097-1104.
• {Nie}, J., {Smith}, M., {Belokurov}, V., {Fan}, X., {Fan}, Z., {Irwin}, M., {Jiang}, Z., {Jing}, Y., {Koposov}, S., {Lesser}, M., {Ma}, J., {Shen}, S., {Wang}, J., {Wu}, Z., {Zhang}, T., {Zhou}, X., {Zhou}, Z., , H. (2015). An Extended View of the Pisces Overdensity from the SCUSS Survey. ApJ, 810, 153.
• {Peng}, X., {Qi}, Z., {Wu}, Z., {Ma}, J., {Du}, C., {Zhou}, X., {Yu}, Y., {Tang}, Z., {Jiang}, Z., {Zou}, H., {Fan}, Z., {Fan}, X., {Smith}, M., {Jiang}, L., {Jing}, Y., {Lattanzi}, M., {McLean}, B., {Lesser}, M., {Nie}, J., , {Shen}, S., et al. (2015). An Investigation of the Absolute Proper Motions of the SCUSS Catalog. PASP, 127, 250-257.
• {Strassmeier}, K., {Ilyin}, I., {J{\"a}rvinen}, A., {Weber}, M., {Woche}, M., {Barnes}, S., {Bauer}, S., {Beckert}, E., {Bittner}, W., {Bredthauer}, R., {Carroll}, T., {Denker}, C., {Dionies}, F., {DiVarano}, I., {D{\"o}scher}, D., {Fechner}, T., {Feuerstein}, D., {Granzer}, T., {Hahn}, T., , {Harnisch}, G., et al. (2015). PEPSI: The high-resolution echelle spectrograph and polarimeter for the Large Binocular Telescope. Astronomische Nachrichten, 336, 324.
• {Zou}, H., {Jiang}, Z., {Zhou}, X., {Wu}, Z., {Ma}, J., {Fan}, X., {Fan}, Z., {He}, B., {Jing}, Y., {Lesser}, M., {Li}, C., {Nie}, J., {Shen}, S., {Wang}, J., {Zhang}, T., , Z. (2015). South Galactic Cap u-band Sky Survey (SCUSS): Data Reduction. AJ, 150, 104.
• {Zou}, H., {Wu}, X., {Zhou}, X., {Wang}, S., {Jiang}, L., {Fan}, X., {Fan}, Z., {Jiang}, Z., {Jing}, Y., {Lesser}, M., {Li}, C., {Ma}, J., {Nie}, J., {Shen}, S., {Wang}, J., {Wu}, Z., {Zhang}, T., , Z. (2015). Capability of Quasar Selection by Combining SCUSS and SDSS Observations. PASP, 127, 94-101.
• Golota, T., De La Peña, M. D., Biddick, C., Lesser, M., Leibold, T., Miller, D., Meeks, R., Hahn, T., Storm, J., & et al., . (2014). Recent developments for the Large Binocular Telescope Guiding Control Subsystem. Proceedings of SPIE - The International Society for Optical Engineering, 9152.
• Jia, Y., Du, C., Wu, Z., Peng, X., Ma, J., Zhou, X., Fan, X., Fan, Z., Jing, Y., & et al., . (2014). Estimation of absolute magnitude-dependent galactic model parameters in intermediate latitude with SDSS and SCUSS. Monthly Notices of the Royal Astronomical Society, 441(1), 503-512.
• Lesser, M. (2014). Silicon sensor quantum efficiency, reflectance, and calibration. Proceedings of SPIE - The International Society for Optical Engineering, 9154.
• Bredthauer, R., Boggs, K., Bredthauer, G., & Lesser, M. (2012). STA1600LN: Low noise 10560 × 10560 pixel high resolution CCD for astronomy. Proceedings of SPIE - The International Society for Optical Engineering, 8453.
  More info

  Abstract: The demand from the astronomical community for high resolution low noise CCDs has led to the development of the STA1600LN, a 10560 × 10560 pixel, 95mm × 95mm, full-frame CCD imager with 9×9 μ2 pixels. The device improvements include noise reduction to below 3e- at 100kHz, improved quantum efficiency, as well as packaging developments for improved fill factor in mosaic systems. We provide test results from production devices, along with updates on scientific systems utilizing the STA1600 for astronomy. © 2012 SPIE.
• Bredthauer, R., Boggs, K., Bredthauer, G., Aamodt, E., Christian, H., Lesser, M., Gheno, K., & Reeve, B. (2012). A novel CCD for application in high frame rate Geostationary space based imaging. Proceedings of SPIE - The International Society for Optical Engineering, 8453.
  More info

  Abstract: The Geostationary Lightning Mapper (GLM) instrument selected to fly on the National Oceanic and Atmospheric Administration (NOAA) GOES-R Series environmental satellites has very unique requirements as compared to an imaging array. GLM's requirements to monitor lightning on a continental scale will provide new insight into the formation, distribution, morphology and evolution of storms. A 500 frame per second backside illuminated frame transfer CCD imager (STA3900A) with variable pixel size has been developed to meet these requirements. A variable pixel architecture provides a near uniform mapping of the curved surface of the earth, while 56 outputs running at 20 MHz yield greater than a 1.1 Gigapixel per second data rate with low RMS noise and high MTF. This paper will provide detailed information on design trades required. We will report CCD read noise, dark current, full well capacity, and quantum efficiency (QE). © 2012 SPIE.
• Iwert, O., Ouellette, D., Lesser, M., & Delabre, B. (2012). First results from a novel curving process for large area scientific imagers. Proceedings of SPIE - The International Society for Optical Engineering, 8453.
  More info

  Abstract: Observations in seeing limited imaging conditions with an extremely large telescope - such as the European Extremely Large Telescope (E-ELT) - will require large detectors and very fast cameras (around F/1.0). The correction of field curvature is a complex task, requiring numerous optical elements operating with high incidence angles. Large format (60 to 90 mm square) concave detectors with a curvature radius between 500 and 250 mm would considerably simplify the optical design, while improving image quality and cutting cost of optical components. Potential applications are not limited to astronomy exclusively. The associated advantages of curved image sensors inside (mosaicked) focal planes have been described in our paper "The challenge of highly curved monolithic imaging detectors", presented at SPIE 2010 [1]. This paper compares in a first step important developments in the area of curving CCD and CMOS detectors using different technical approaches linked to specific thinning processes with a novel approach followed after ESO's initial feasibility study: First results of the latter are described with a report on the chosen curving technology aimed at producing 500 to 250 mm radius of curvature silicon detectors of approximately 60 mm square format (typical astronomical 4k × 4k CCDs). The curvature technique has been developed for front-illuminated devices with the goal of extending the process to back-illuminated sensors in the near future. We will discuss the fabrication process of curving the devices as well as the difficulties encountered during development. Characterization results from a curved detector, including metrology, and electrical performance before and after curvature are presented. © 2012 SPIE.
• Lesser, M. (2012). Recent astronomical detector development at the University of Arizona. Proceedings of SPIE - The International Society for Optical Engineering, 8453.
  More info

  Abstract: The University of Arizona Imaging Technology Laboratory (ITL) has been developing back illuminated detectors and detector technologies for several astronomical projects in recent years. These projects include the WIYN telescope One Degree Imager (ODI) mosaic of Orthogonal Transfer Array CCDs, the VIRUS detectors for the University of Texas' Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), detector and packaging development for the Large Synoptic Survey Telescope (LSST), and 10k×10k and 4k×4k CCDs for several instruments. In this paper we discuss these projects with an emphasis on backside processing issues and detector characterization results which may be relevant to other groups. We will also focus packaging techniques and metrology for achieving very flat and stable focal planes. Results will include device flatness at cryogenic temperatures, process yield, photo-response non-uniformity and cosmetics, quantum efficiency, read noise, linearity, charge transfer efficiency, and photon transfer data. © 2012 SPIE.
• Sawyer, D., Ouellette, D., Martin, P. M., Lesser, M., Jacoby, G. H., Harbeck, D., Cavin, J., Bredthauer, R., Boroson, T. A., & Boggs, K. (2012). Characterization of orthogonal transfer array CCDs for the WIYN one degree imager. Proceedings of SPIE, 8298. doi:10.1117/12.908376
  More info

  The WIYN One Degree Imager (ODI) will provide a one degree field of view for the WIYN 3.5 m telescope located on Kitt Peak near Tucson, Arizona. Its focal plane consists of an 8x8 grid of Orthogonal Transfer Array (OTA) CCD detectors. These detectors are the STA2200 OTA CCDs designed and fabricated by Semiconductor Technology Associates, Inc. and backside processed at the University of Arizona Imaging Technology Laboratory. Several lot runs of the STA2200 detectors have been fabricated. We have backside processed devices from these different lots and provide detector performance characterization, including noise, CTE, cosmetics, quantum efficiency, and some orthogonal transfer characteristics. We discuss the performance differences for the devices with different silicon thickness and resistivity. A fully buttable custom detector package has been developed for this project which allows hybridization of the silicon detectors directly onto an aluminum nitride substrate with an embedded pin grid array. This package is mounted on a silicon-aluminum alloy which provides a flat imaging surface of less than 20 microns peakvalley at the -100 C operating temperature. Characterization of the package performance, including low temperature profilometry, is described in this paper.
• Etoh, T. G., Nguyen, D. H., V., S., Vo, C. L., Tanaka, M., Takehara, K., Okinaka, T., Kuijk, H. V., Klaassens, W., Bosiers, J., Lesser, M., Ouellette, D., Maruyama, H., Hayashida, T., & Arai, T. (2011). A 16 Mfps 165kpixel backside-illuminated CCD. Digest of Technical Papers - IEEE International Solid-State Circuits Conference, 406-407.
  More info

  Abstract: In 2002, we reported a CCD image sensor with 260x312 pixels capable of capturing 103 consecutive images at 1,000,000 frames per second (1Mfps) [1]. We named the sensor "ISIS-V2", for In-situStorage Image Sensor Version 2. 103 memory elements are attached to every pixel; generated image signals were instantly and continuously stored in the in-situstorage without being read out of the sensor. The ultimate high-speed recording was enabled by this parallel recording at all pixels. In 2006, the color version, ISIS-V4, was reported [2]. In 2009, we developed ISIS-V12, a backside-illuminated image sensor mounting the ISIS structure and the CCM, charge-carrier multiplication, on the front side [3]. The CCM is a CCD-specific efficient signal-amplification device. CCM, combined with the BSI structure and cooling, achieved very high sensitivity. The ISIS-V12 was a test sensor intended to prove the technical feasibility of the structure. The maximum frame rate was 250kfps for a charge-handling capacity of Qmax=10,000e- and 1Mfps for a reduced Qmax. The pixel count was 489x400 pixels. For backside-illuminated (BSI) image sensors, metal wires can be placed on the front surface to increase the frame rate without reducing fill factor or violating uniformity of the pixel configuration. It has been proved by simulations that 100Mfps is achievable by introducing innovative technologies including a special wiring method [4]. We now report on ISIS-V16, developed by incorporating technologies to increase the frame rate with those to achieve very high sensitivity, which was confirmed by evaluation of ISIS-V12. The performance specification of ISIS-V16 is summarized in Fig. 23.4.1. © 2011 IEEE.
• Le, C. V., Etoh, T. G., Nguyen, H. D., Dao, V. T., Soya, H., Lesser, M., Ouellette, D., Kuijk, H. v., Bosiers, J., & Ingram, G. (2009). A backside-illuminated image sensor with 200000 pixels operating at 250000 frames per second. IEEE Transactions on Electron Devices, 56(11), 2556-2562.
  More info

  Abstract: In this paper, a high-speed image sensor with very high sensitivity is developed. The high sensitivity is achieved by introduction of backside illumination and charge-carrier multiplication (CCM). The high frame rate is guaranteed by installing the in situ storage image sensor (ISIS) structure on the front side. A test sensor of the BSI-ISIS has been developed and evaluated. It is shown that an image with a very low signal level embedded under the noise floor is recognizable by activating the CCM. © 2009 IEEE.
• Lesser, M., Ouellette, D., Zareba, G., Jacoby, G., Muller, G., Sawyer, D., Keyes, J., Bredthauer, R., & Boggs, K. (2009). Packaging and characterization of orthogonal transfer array CCDs for the WIYN One Degree Imager. Proceedings of SPIE - The International Society for Optical Engineering, 7249.
  More info

  Abstract: The WIYN One Degree Imager (ODI) will provide a one degree field of view for the WIYN 3.5 m telescope located on Kitt Peak near Tucson, Arizona. Its focal plane will consist of an 8×8 grid of Orthogonal Transfer Array (OTA) CCD detectors with nearly one billion pixels. The implementation of these detectors into the focal plane has required the development of several novel packaging and characterization techniques, which are the subject of this paper. We describe a new packaging/hybridization method in which the CCD die are directly bonded to aluminum nitride ceramic substrates which have indium bump on one side and brazed pins on the other. These custom packages allow good thermal conductivity, a flat imaging surface, four side buttability, and in situ testing of the devices during backside processing. We describe these carriers and the backside processing techniques used with them. We have also modified our cold probing system to screen these OTA die at wafer level to select the best candidates for backside processing. We describe these modifications and characterization results from several wafer lots. © 2009 SPIE-IS&T.
• Nguyen, H. D., Vo-Le, C., Dao, V. T., Takehara, K., Etoh, T. G., Kondo, Y., Maruno, H., Tominaga, H., Soya, H., Kuijk, H. V., Bosiers, J., Klaassens, W., Ingram, G., Singh, S., & Lesser, M. (2009). Evaluation of a backside-illuminated ISIS. Proceedings of SPIE - The International Society for Optical Engineering, 7126.
  More info

  Abstract: This paper presents preliminary evaluation results of a test sensor of the backside-illuminated ISIS, an ultra-high sensitivity and ultra-high speed CCD image sensor. To achieve ultra-high sensitivity, the CCD image sensor employs the following three technologies: backside illumination, cooling and Charge Carrier Multiplication (CCM). The test sensor has been designed, fabricated and evaluated. At room temperature without cooling, the video camera has about ten-time higher sensitivity than the previous one, which was supported by a conventional front side illumination technology. Furthermore, the video camera can detect images at very low signal level, less than 5 e-, by using CCM at -40 degree C. © 2009 SPIE.
• Lesser, M., & Tucker, R. (2008). Characterization of wafer-scale and many-output CCD detectors. Proceedings of SPIE - The International Society for Optical Engineering, 7021.
  More info

  Abstract: The latest CCD detectors destined for advanced astronomical instruments are larger and have more output amplifiers than previous devices. Examples are the Semiconductor Technology Associates, Inc. 16-output STA1600 and STA1900 devices and the 8-output STA2200 Orthogonal Transfer Array CCDs. Back illuminated versions of these devices have been processed and evaluated at the University of Arizona Imaging Technology Laboratory and are the subject of this paper. Characterizing these devices has required new optical testing equipment and optimized techniques to efficiently evaluate device performance. This is especially true when even limited volume production is required. In this paper we discuss the hardware related to characterization of the large format (135 mm diagonal) and 8- and 16- output CCDs at cold temperatures, including quantum efficiency, charge transfer efficiency, noise, full well, cross-talk, and operating parameters. We also discuss related developments in dewar construction and operation, including a hybrid closed cycle and liquid nitrogen cooling system used for long-term testing, the characterization optical system, and related device packaging. We also describe the equipment for wafer level probe testing of the same devices.
• Strassmeier, K. G., Woche, M., Ilyin, I., Popow, E., Bauer, S. M., Dionies, F., Fechner, T., Weber, M., Hofmann, A., Storm, J., Materne, R., Bittner, W., Bartus, J., Granzer, T., Denker, C., Carroll, T., Kopf, M., DiVarano, I., Beckert, E., & Lesser, M. (2008). PEPSI: The Potsdam Echelle Polarimetric and Spectroscopic Instrument for the LBT. Proceedings of SPIE - The International Society for Optical Engineering, 7014.
  More info

  Abstract: We present the status of PEPSI, the bench-mounted fibre-fed and stabilized "Potsdam Echelle Polarimetric and Spectroscopic Instrument" for the 2×8.4m Large Binocular Telescope in southern Arizona. PEPSI is under construction at AIP and is scheduled for first light in 2009/10. Its ultra-high-resolution mode will deliver an unprecedented spectral resolution of approximately R=310,000 at high efficiency throughout the entire optical/red wavelength range 390-1050nm without the need for adaptive optics. Besides its polarimetric Stokes IQUV mode, the capability to cover the entire optical range in three exposures at resolutions of 40,000, 130,000 and 310,000 will surpass all existing facilities in terms of light-gathering-power times spectral-coverage product. A solar feed will make use of the spectrograph also during day time. As such, we hope that PEPSI will be the most powerful spectrometer of its kind for the years to come.
• Boggs, K., Bredthauer, R., & Lesser, M. (2007). Development of fully depleted scientific CCD's for astronomy. Proceedings of SPIE - The International Society for Optical Engineering, 6501.
  More info

  Abstract: Due to aggressive scientific specifications, Semiconductor Technology Associates and the University of Arizona's Imaging Technology Laboratory have collaborated to develop a fully depleted back illuminated CCD for scientific imaging. These devices are designed to target increased quantum efficiency into the near-infrared, without reduction in the modulation transfer function, charge transfer efficiency, or rms noise. The STA1700 series imagers are back illuminated 100 micron thick devices with a 10 micron pixel pitch targeted to meet the requirements of the Large Synoptic Survey Telescope (LSST). Recent characterization results will be presented including the point spread function of a 2 micron spot. Also discussed will be the thinning and packaging developments for the STA1700. These efforts include the addition of a backside bias contact, invar package design with high density connectors, as well as etching and backside coating optimization for high resistivity silicon. © 2007 SPIE-IS&T.
• Janesick, J., Andrews, J., Tower, J., Grygon, M., Elliott, T., Cheng, J., Lesser, M., & Pinter, J. (2007). Fundamental performance differences between CMOS and CCD imagers; Part II. Proceedings of SPIE - The International Society for Optical Engineering, 6690.
  More info

  Abstract: A new class of CMOS imagers that compete with scientific CCDs is presented. The sensors are based on deep depletion backside illuminated technology to achieve high near infrared quantum efficiency and low pixel cross-talk. The imagers deliver very low read noise suitable for single photon counting - Fano-noise limited soft x-ray applications. Digital correlated double sampling signal processing necessary to achieve low read noise performance is analyzed and demonstrated for CMOS use. Detailed experimental data products generated by different pixel architectures (notably 3TPPD, 5TPPD and 6TPG designs) are presented including read noise, charge capacity, dynamic range, quantum efficiency, charge collection and transfer efficiency and dark current generation. Radiation damage data taken for the imagers is also reported.
• Randall, S. K., Green, E. M., Grootel, V. V., Fontaine, G., Charpinet, S., Lesser, M., Brassard, P., Sugimoto, T., Chayer, P., Fay, A., Wroblewski, P., Daniel, M., Story, S., & Fitzgerald, T. (2007). Observations and asteroseismic analysis of the rapidly pulsating hot B subdwarf PG 0911+456. Astronomy and Astrophysics, 476(3), 1317-1329.
  More info

  Abstract: Aims.The principal aim of this project is to determine the structural parameters of the rapidly pulsating subdwarf B star PG 0911+456 from asteroseismology. Our work forms part of an ongoing programme to constrain the internal characteristics of hot B subdwarfs with the long-term goal of differentiating between the various formation scenarios proposed for these objects. So far, a detailed asteroseismic interpretation has been carried out for 6 such pulsators, with apparent success. First comparisons with evolutionary theory look promising, however it is clear that more targets are needed for meaningful statistics to be derived.Methods.The observational pulsation periods of PG 0911+456 were extracted from rapid time-series photometry using standard Fourier analysis techniques. Supplemented by spectroscopic estimates of the star's mean atmospheric parameters, they were used as a basis for the "forward modelling" approach in asteroseismology. The latter culminates in the identification of one or more "optimal" models that can accurately reproduce the observed period spectrum. This naturally leads to an identification of the oscillations detected in terms of degree and radial order , and infers the structural parameters of the target.Results.The high S/N low- and medium resolution spectroscopy obtained led to a refinement of the atmospheric parameters for PG 0911+456, the derived values being = 31 940 220 K, log = 5.767 0.029, and log He/H = -2.548 0.058. From the photometry it was possible to extract 7 independent pulsation periods in the 150-200 s range with amplitudes between 0.05 and 0.8% of the star's mean brightness. There was no indication of fine frequency splitting over the ∼68-day time baseline, suggesting a very slow rotation rate. An asteroseismic search of parameter space identified several models that matched the observed properties of PG 0911+456 well, one of which was isolated as the "optimal" model on the basis of spectroscopic and mode identification considerations. All the observed pulsations are identified with low-order acoustic modes with degree indices = 0,1,2 and 4, and match the computed periods with a dispersion of only ∼0.26%, typical of the asteroseismological studies carried out to date for this type of star. The inferred structural parameters of PG 0911+456 are = 31 940 220 K (from spectroscopy), log = 5.777 0.002, = 0.39 0.01, log = -4.69 0.07, = 0.133 0.001 and = 16.4 0.8. We also derive the absolute magnitude = 4.82 0.04 and a distance = 930.3 27.4 pc.. © 2007 ESO.
• Zacharias, N., Dorland, B., Bredthauer, R., Boggs, K., Bredthauer, G., & Lesser, M. (2007). Realization and application of a 111 million pixel backside-illuminated detector and camera. Proceedings of SPIE - The International Society for Optical Engineering, 6690.
  More info

  Abstract: A full-wafer, 10,580 × 10,560 pixel (95 × 95 mm) CCD was designed and tested at Semiconductor Technology Associates (STA) with 9 μm. square pixels and 16 outputs. The chip was successfully fabricated in 2006 at DALSA and some performance results are presented here. This program was funded by the Office of Naval Research through a Small Business Innovation in Research (SBIR) program requested by the U.S. Naval Observatory for its next generation astrometric sky survey programs. Using Leach electronics, low read-noise output of the 111 million pixels requires 16 seconds at 0.9 MHz. Alternative electronics developed at STA allow readout at 20 MHz. Some modifications of the design to include anti-blooming features, a larger number of outputs, and use of p-channel material for space applications are discussed.
• Golimowski, D. A., Ardila, D. R., Krist, J. E., Clampin, M., Ford, H. C., Illingworth, G. D., Bartko, F., Benítez, N., Blakeslee, J. P., Bouwens, R. J., Bradley, L. D., Broadhurst, T. J., Brown, R. A., Burrows, C. J., Cheng, E. S., Cross, N. J., Demarco, R., Feldman, P. D., Franx, M., , Goto, T., et al. (2006). Rubble space telescope ACS multiband coronagraphic imaging of the debris disk around β pictoris. Astronomical Journal, 131(6), 3109-3130.
  More info

  Abstract: We present F435W (B), F606W (broad V), and F814W (broad I) coronagraphic images of the debris disk around β Pictoris obtained with the Hubble Space Telescope's Advanced Camera for Surveys. These images provide the most photometrically accurate and morphologically detailed views of the disk between 30 and 300 AU from the star ever recorded in scattered light. We confirm that the previously reported warp in the inner disk is a distinct secondary disk inclined by ∼5° from the main disk. The projected spine of the secondary disk coincides with the isophotal inflections, or "butterfly asymmetry," previously seen at large distances from the star. We also confirm that the opposing extensions of the main disk have different position angles, but we find that this "wing-tilt asymmetry" is centered on the star rather than offset from it, as previously reported. The main disk's northeast extension is linear from 80 to 250 AU, but the southwest extension is distinctly bowed with an amplitude of ∼ 1 AU over the same region. Both extensions of the secondary disk appear linear, but not collinear, from 80 to 150 AU. Within ∼120 AU of the star, the main disk is ∼50% thinner than previously reported. The surface brightness profiles along the spine of the main disk are fitted with four distinct radial power laws between 40 and 250 AU, while those of the secondary disk between 80 and 150 AU are fitted with single power laws. These discrepancies suggest that the two disks have different grain compositions or size distributions. The F606W/F435W and F814W/F435 W flux ratios of the composite disk are nonuniform and asymmetric about both projected axes of the disk. The disk's northwest region appears 20%-30% redder than its southeast region, which is inconsistent with the notion that forward scattering from the nearer northwest side of the disk should diminish with increasing wavelength. Within ∼120 AU, the m F435W- m F606Wand m F435W - m F814W colors along the spine of the main disk are ∼10% and ∼20% redder, respectively, than those of β Pic. These colors increasingly redden beyond ∼120 AU, becoming 25% and 40% redder, respectively, than the star at 250 AU. These measurements overrule previous determinations that the disk is composed of neutrally scattering grains. The change in color gradient at ∼ 120 AU nearly coincides with the prominent inflection in the surface brightness profile at ∼ 115 AU and the expected waterice sublimation boundary. We compare the observed red colors within ∼ 120 AU with the simulated colors of nonicy grains having a radial number density αr -3 and different compositions, porosities, and minimum grain sizes. The observed colors are consistent with those of compact or moderately porous grains of astronomical silicate and/or graphite with sizes ≳0.15-0.20 μm, but the colors are inconsistent with the blue colors expected from grains with porosities ≳90%. The increasingly red colors beyond the ice sublimation zone may indicate the condensation of icy mantles on the refractory grains, or they may reflect an increasing minimum grain size caused by the cessation of cometary activity. © 2006. The American Astronomical Society. All rights reserved.
• Lesser, M., & Ouellette, D. (2006). Development of hybridized focal plane technologies. Proceedings of SPIE - The International Society for Optical Engineering, 6276.
  More info

  Abstract: Large area focal planes for the next generation of astronomical instruments require very flat imaging surfaces (< 10 μm peak-valley) over significant sizes (20 - 100 cm), accurate alignment of detector height, stable operation at low temperature, and fully-buttable packaging with large I/O requirements to connect multiple amplifiers per detector. These requirements are often mutually exclusive and therefore difficult to obtain in a single focal plane. In this paper we discuss the hybridization or flip chip bonding technique and associated focal plane mounting methods to achieve these goals. Specifically, we describe a technique to hybridize CCD detectors onto high thermal conductivity ceramic with vias that lead to the I/O signals underneath the detectors. Packaging methods to mount such devices with a total flatness non-uniformity of less than 10 microns are presented. The requirements of achieving sub-5 microns flatness are also discussed.
• Mei, S., Blakeslee, J. P., Stanford, S. A., Holden, B. P., Rosati, P., Sirazzullo, V., Homeier, N., Postman, M., Franx, M., Rettura, A., Ford, H., Illingworth, G. D., Eitori, S., Bouwens, R. J., Demarco, R., Martel, A. R., Clampin, M., Hartig, G. F., Eisenhardt, P., , Ardila, D. R., et al. (2006). Evolution of the color-magnitude relation in high-redshift clusters: blue early-type galaxies and red pairs in RDCS J0910+5422. Astrophysical Journal Letters, 639(1 I), 81-94.
  More info

  Abstract: The color-magnitude relation has been determined for the RDCS J0910+5422 cluster of galaxies at redshift z = 1.106. Cluster members were selected from the Hubble Space Telescope Advanced Camera for Surveys (HST ACS) images, combined with ground-based near-IR imaging and optical spectroscopy. The observed early-type color-magnitude relation (CMR) in i775 - z 850 versus z850 shows an intrinsic scatter in color of 0.060 ± 0.009 mag, within 1′ from the cluster X-ray emission center. Both the elliptical and the S0 galaxies show small scatter about the CMR of 0.042 ± 0.010 and 0.044 ± 0.020 mag, respectively. From the scatter about the CMR, a mean luminosity-weighted age t̄ > 3.3 Gyr (zf ≈ 3) is derived for the elliptical galaxies, assuming a simple stellar population modeling (single-burst solar metallicity). Strikingly, the S0 galaxies in RDCS J0910+5422 are systematically bluer in i775 - z850, by 0.07 ± 0.02 mag, than the ellipticals. The ellipticity distribution as a function of color indicates that the face-on S0s in this particular cluster have likely been classified as elliptical. Thus, if anything, the offset in color between the elliptical and S0 populations may be even more significant. The color offset between S0 and E galaxies corresponds to an age difference of ≈1 Gyr for a single-burst solar-metallicity model. A solar-metallicity model with an exponential decay in star formation will reproduce the offset for an age of 3.5 Gyr; i.e., the S0s have evolved gradually from star-forming progenitors. The early-type population in this cluster appears to be still forming. The blue early-type disk galaxies in RDCS J0910+5422 likely represent the direct progenitors of the more evolved S0s that follow the same red sequence as elliptical galaxies in other clusters. Thirteen red galaxy pairs are observed, and the galaxies associated in pairs constitute ∼40% of the CMR galaxies in this cluster. © 2006. The American Astronomical Society. All rights reserved.
• Tower, J. R., Pinter, J. H., Lesser, M., Janesick, J., Grygon, M., Elliott, T., Cheng, J., & Andrews, J. T. (2006). Fundamental performance differences between CMOS and CCD imagers: Part II. Proceedings of SPIE, 7439. doi:10.1117/12.678867
  More info

  This paper is a status report on recent scientific CMOS imager developments since when previous publications were written. Focus today is being given on CMOS design and process optimization because fundamental problems affecting performance are now reasonably well understood. Topics found in this paper include discussions on a low cost custom scientific CMOS fabrication approach, substrate bias for deep depletion imagers, near IR and x-ray point-spread performance, custom fabricated high resisitivity epitaxial and SOI silicon wafers for backside illuminated imagers, buried channel MOSFETs for ultra low noise performance, 1 e- charge transfer imagers, high speed transfer pixels, RTS/ flicker noise versus MOSFET geometry, pixel offset and gain non uniformity measurements, high S/N dCDS/aCDS signal processors, pixel thermal dark current sources, radiation damage topics, CCDs fabricated in CMOS and future large CMOS imagers planned at Sarnoff.
• Zheng, W., Overzier, R. A., Bouwens, R. J., White, R. L., Ford, H. C., Beníez, N., Blakeslee, J. P., Bradley, L. D., Jee, M. J., Martel, A. R., Mei, S., Zirm, A. W., Illingworth, G. D., Clampin, M., Hartig, G. F., Ardila, D. R., Bartko, F., Broadhurst, T. J., Brown, R. A., , Burrows, C. J., et al. (2006). An overdensity of galaxies near the most distant radio-loud quasar. Astrophysical Journal Letters, 640(2 I), 574-578.
  More info

  Abstract: A 5 arcmin2 region around the luminous radio-loud quasar SDSS J0836+0054 (z = 5.8) hosts a wealth of associated galaxies, characterized by very red (1.3 < i775 - z850 < 2.0) color. The surface density of these z ∼ 5.8 candidates is approximately 6 times higher than the number expected from deep ACS fields. This is one of the highest galaxy overdensities at high redshifts, which may develop into a group or cluster. We also find evidence for a substructure associated with one of the candidates. It has two very faint companion objects within 2″, which are likely to merge. The finding supports the results of a recent simulation, which finds that luminous quasars at high redshifts lie on the most prominent dark matter filaments and are surrounded by many fainter galaxies. The quasar activity from these regions may signal the buildup of a massive system. © 2006 The American Astronomical Society. All rights reserved.
• Ardila, D. R., Lubow, S. H., Golimowski, D. A., Krist, J. E., Clampin, M., Ford, H. C., Hartig, G. F., Illingworth, G. D., Bartko, F., Benitez, N., Blakeslee, J. P., Bouwens, R. J., Bradley, L. D., Broadhurst, T. J., Brown, R. A., Burrows, C. J., Cheng, E. S., Cross, N. J., Feldman, P. D., , Franx, M., et al. (2005). A dynamical simulation of the debris disk around HD 141569A. Astrophysical Journal Letters, 627(2 I), 986-1000.
  More info

  Abstract: We study the dynamical origin of the structures observed in the scattered-light images of the resolved debris disk around HD 141569A. The disk has two conspicuous spiral rings and two large-scale spiral arms. We explore the roles of radiation pressure from the central star, gas drag from the gas disk, and the tidal forces from two nearby stars in creating and maintaining these structures. The disk's color, scattering function, and infrared emission suggest that submicron-sized grains dominate the dust population observed in scattered light. CO observations indicate the presence of up to 60 M⊕ of gas. The dust grains are subject to the competing effects of expulsive radiation pressure (β > 1, where β is the ratio of the radiation and gravitational forces) and retentive gas drag. We use a simple one-dimensional axisymmetric model to show that the presence of the gas helps confine the dust and that a broad ring of dust is produced if a central hole exists in the disk. This model also suggests that the disk is in a transient, excited dynamical state, as the observed dust creation rate applied over the age of the star is inconsistent with submillimeter mass measurements. We model in two dimensions the effects of a flyby encounter between the disk and a binary star in a prograde, parabolic, coplanar orbit. We track the spatial distribution of the disk's gas, planetesimals, and dust. We conclude that the surface density distribution reflects the planetesimal distribution for a wide range of parameters. Our most viable model features a disk with initial radius 400 AU, a gas mass of 50 M⊕, and β= 4 and suggests that the system is being observed within 4000 yr of the flyby periastron. The model reproduces some features of HD 141569A's disk, such as a broad single ring and large spiral arms, but it does not reproduce the observed multiple spiral rings or disk asymmetries nor the observed clearing in the inner disk. For the latter, we consider the effect of a 5MJ planet in an eccentric orbit on the planetesimal distribution of HD 141569A. © 2005. The American Astronomical Society. All rights reserved.
• Bartko, F., Zheng, W., Zekser, K. C., White, R. L., Tsvetanov, Z. I., Tran, H. D., Steindling, S., Sparks, W. B., Sirianni, M., Sharon, K., Rosati, P., Postman, M., Miley, G. K., Meurer, G. R., Menanteau, F., Martel, A. R., Lesser, M. P., Krist, J. E., Infante, L., , Illingworth, G. D., et al. (2005). STRONG-LENSING ANALYSIS OF A1689 FROM DEEP ADVANCED CAMERA IMAGES. The Astrophysical Journal, 621(1), 53-88. doi:10.1086/426494
  More info

  We analyze deep multicolor Advanced Camera images of the largest known gravitational lens, A1689. Radial and tangential arcs delineate the critical curves in unprecedented detail, and many small counterimages are found near the center of mass. We construct a flexible light deflection field to predict the appearance and positions of counterimages. The model is refined as new counterimages are identified and incorporated to improve the model, yielding a total of 106 images of 30 multiply lensed background galaxies, spanning a wide redshift range, 1.0 < z < 5.5. The resulting mass map is more circular in projection than the clumpy distribution of cluster galaxies, and the light is more concentrated than the mass within r < 50 kpc h-1. The projected mass profile flattens steadily toward the center with a shallow mean slope of d log ?/d log r -0.55 ? 0.1, over the observed range r < 250 kpc h-1, matching well an NFW profile, but with a relatively high concentration, Cvir = 8.2. A softened isothermal profile (rcore = 20 ? 2'') is not conclusively excluded, illustrating that lensing constrains only projected quantities. Regarding cosmology, we clearly detect the purely geometric increase of bend angles with redshift. The dependence on the cosmological parameters is weak owing to the proximity of A1689, z = 0.18, constraining the locus, ?M + ?? ? 1.2. This consistency with standard cosmology provides independent support for our model, because the redshift information is not required to derive an accurate mass map. Similarly, the relative fluxes of the multiple images are reproduced well by our best-fitting lens model.
• Broadhurst, T., Benítez, N., Coe, D., Sharon, K., Zekser, K., White, R., Ford, H., Bouwens, R., Blakeslee, J., Clampin, M., Cross, N., Franx, M., Frye, B., Hartig, G., Illingworth, G., Infante, L., Menanteau, F., Meurer, G., Postman, M., , Ardila, D. R., et al. (2005). Strong-lensing analysis of A1689 from deep advanced camera images. Astrophysical Journal Letters, 621(1 I), 53-88.
  More info

  Abstract: We analyze deep multicolor Advanced Camera images of the largest known gravitational lens, A1689. Radial and tangential arcs delineate the critical curves in unprecedented detail, and many small counterimages are found near the center of mass. We construct a flexible light deflection field to predict the appearance and positions of counterimages. The model is refined as new counterimages are identified and incorporated to improve the model, yielding a total of 106 images of 30 multiply lensed background galaxies, spanning a wide redshift range, 1.0 < z < 5.5. The resulting mass map is more circular in projection than the clumpy distribution of cluster galaxies, and the light is more concentrated than the mass within r < 50 kpc h-1. The projected mass profile flattens steadily toward the center with a shallow mean slope of d log Σ/dlog r≃-0.55±0.1, over the observed range r < 250 kpc h-1, matching well an NFW profile, but with a relatively high concentration, Cvir = 8.2-1.8+2.1. A softened isothermal profile (rcore = 20 ± 2″) is not conclusively excluded, illustrating that lensing constrains only projected quantities. Regarding cosmology, we clearly detect the purely geometric increase of bend angles with redshift. The dependence on the cosmological parameters is weak owing to the proximity of A1689, z = 0.18, constraining the locus, ΩM + Ωλ < 1.2. This consistency with standard cosmology provides independent support for our model, because the redshift information is not required to derive an accurate mass map. Similarly, the relative fluxes of the multiple images are reproduced well by our best-fitting lens model. © 2005. The American Astronomical Society. All rights reserved.
• Goto, T., Postman, M., J., N., Illingworth, G. D., Tran, K., Magee, D., Franx, M., Benítez, N., Bouwens, R. J., Demarco, R., Ford, H. C., Homeier, N. L., Martel, A. R., Menanteau, F., Clampin, M., Hartig, G. F., Ardila, D. R., Bartko, F., Blakeslee, J. P., , Bradley, L. D., et al. (2005). Luminosity functions of the galaxy cluster MS 1054-0321 at z = 0.83 based on ACS photometry. Astrophysical Journal Letters, 621(1 I), 188-200.
  More info

  Abstract: We present new measurements of the galaxy luminosity function (LF) and its dependence on local galaxy density, color, morphology, and clustocentric radius for the massive z = 0.83 cluster MS 1054-0321. Our analyses are based on imaging performed with the Advanced Camera for Surveys (ACS) on board the Rubble Space Telescope (HST) in the F606W, F775W, and F850LP passbands and extensive spectroscopic data obtained with the Keck Low-Resolution Imaging Spectrograph. Our main results are based on a spectroscopically selected sample of 143 cluster members with morphological classifications derived from the ACS observations. Our three primary findings are (1) the faint-end slope of the LF is steepest in the bluest filter, (2) the LF in the inner part of the cluster (or highest density regions) has a flatter faint-end slope, and (3) the fraction of early-type galaxies is higher at the bright end of the LF, and gradually decreases toward fainter magnitudes. These characteristics are consistent with those in local galaxy clusters, indicating that, at least in massive clusters, the common characteristics of cluster LFs are established at z = 0.83. These results provide additional support for the hypothesis that the formation of galaxies in MS 1054-0321 began at redshifts considerably greater than unity. We also find a 2 σ deficit of intrinsically faint, red galaxies (i 775 - z850 ≥ 0.5, Mi > -19) in this cluster. Although the significance is marginal, this trend may suggest that faint, red galaxies (which are common in z < 0.1 rich clusters) have not yet been created in this cluster at z = 0.83. The giant-to-dwarf ratio in MS 1054-0321 starts to increase inwards of the virial radius or when Σ > 30 Mpc-2, coinciding with the environment where the galaxy star formation rate and the morphology-density relation start to appear. A physical process that begins to become effective at around the virial radius or Σ ∼ 30 Mpc-2 may thus be responsible for the evolution of color and luminosity of cluster galaxies. © 2005. The American Astronomical Society. All rights reserved.
• Holden, B. P., Blakeslee, J. P., Postman, M., Illingworth, G. D., Demarco, R., Pranx, M., Rosati, P., Bouwens, R. J., Martel, A. R., Ford, H., Clampin, M., Hartig, G. F., Benítez, N., Cross, N. J., Homeier, N., Lidman, C., Menanteau, F., Zirm, A., Ardila, D. R., , Bartko, F., et al. (2005). Evolution in the cluster early-type galaxy size-surface brightness relation at z ≃ 1. Astrophysical Journal Letters, 626(2 I), 809-822.
  More info

  Abstract: We investigate the evolution in the distribution of surface brightness, as a function of size, for elliptical and S0 galaxies in the two clusters RDCS J1252.9-2927 (z = 1.237) and RX J0152.7-1357 (z = 0.837). We use multi-color imaging with the Advanced Camera for Surveys on the Hubble Space Telescope to determine these sizes and surface brightnesses. Using three different estimates of the surface brightnesses, we find that we reliably estimate the surface brightness for the galaxies in our sample with a scatter of
• Homeier, N. L., Demarco, R., Rosati, P., Postman, M., Blakeslee, J. P., Bouwens, R. J., Bradley, L. D., Ford, H. C., Goto, T., Gronwall, C., Holden, B., Jee, M. J., Martel, A. R., Mei, S., Menanteau, F., Zirm, A., Clampin, M., Hartig, G. F., Illingworth, G. D., , Ardila, D. R., et al. (2005). The transformation of cluster galaxies at intermediate redshift. Astrophysical Journal Letters, 621(2 I), 651-662.
  More info

  Abstract: We combine imaging data from the Advanced Camera for Surveys (ACS) with VLT/FORS optical spectroscopy to study the properties of star-forming galaxies in the z = 0.837 cluster Cl 0152-1357. We have morphological information for 24 star-forming cluster galaxies, which range in morphology from late-type and irregular to compact early-type galaxies. We find that while most star-forming galaxies have r625-i775 colors bluer than 1.0, eight are in the red cluster sequence. Among the star-forming cluster population, we find five compact early-type galaxies that have properties consistent with their identification as progenitors of dwarf elliptical galaxies. The spatial distribution of the star-forming cluster members is nonuniform. We find none within R ∼ 500 Mpc of the cluster center, which is highly suggestive of an intracluster medium interaction. We derive star formation rates from [O II] λ3727 line fluxes and use these to compare the global star formation rate of Cl 0152-1357 to other clusters at low and intermediate redshifts. We find a tentative correlation between integrated star formation rates and T X, in the sense that hotter clusters have lower integrated star formation rates. Additional data from clusters with low X-ray temperatures are needed to confirm this trend. We do not find a. significant correlation with redshift, suggesting that evolution is either weak or absent between z = 0.2 and 0.8. © 2005, The American Astronomical Society, All rights reserved.
• Krist, J. E., Ardila, D. R., Golimowski, D. A., Clampin, M., Ford, H. C., Illingworth, G. D., Hartig, G. F., Bartko, F., Benítez, N., Blakeslee, J. P., Bouwens, R. J., Bradley, L. D., Broadhurst, T. J., Brown, R. A., Burrows, C. J., Cheng, E. S., Cross, N. J., Demarco, R., Feldman, P. D., , Franx, M., et al. (2005). Hubble Space Telescope Advanced Camera for Surveys coronagraphic imaging of the AU Microscopii debris disk. Astronomical Journal, 129(2), 1008-1017.
  More info

  Abstract: We present Hubble Space Telescope Advanced Camera for Surveys multicolor coronagraphic images of the recently discovered edge-on debris disk around the nearby (∼10 pc) M dwarf AU Microscopii. The disk is seen between r = 0″75 and 15″ (7.5-150 AU) from the star. It has a thin midplane with a projected FWHM thickness of 2.5-3.5 AU within r < 50 AU of the star that increases to 6.5-9 AU at r ∼ 75 AU. The disk's radial brightness profile is generally flat for r < 15 AU, then decreases gradually (I ∝ r -1.8) out to r ≈ 43 AU, beyond which it falls rapidly (I ∝ r -4.7). Within 50 AU the midplane is straight and aligned with the star, and beyond that it deviates by ∼3°, resulting in a bowed appearance that was also seen in ground-based images. Three-dimensional modeling of the disk shows that the inner region (r < 50 AU) is inclined to the line of sight by less than 1° and the outer disk by ∼3°. The inclination of the outer disk and moderate forward scattering (g ≈ 0.4) can explain the apparent bow. The intrinsic, deprojected FWHM thickness is 1.5-10 AU, increasing with radius. The models indicate that the disk is clear of dust within ∼12 AU of the star, in general agreement with the previous prediction of 17 AU based on the infrared spectral energy distribution. The disk is blue, being 60% brighter at B than I relative to the star. One possible explanation for this is that there is a surplus of very small grains compared with other imaged debris disks that have more neutral or red colors. This may be due to the low radiation pressure exerted by the late-type star. Observations at two epochs show that an extended source seen along the midplane is a background galaxy. © 2005. The American Astronomical Society. All rights reserved.
• Postman, M., Franx, M., Cross, N. J., Holden, B., Ford, H. C., Illingworth, G. D., Goto, T., Demarco, R., Rosati, P., Blakeslee, J. P., Tran, K. -., Benitez, N., Clampin, M., Hartig, G. F., Homeier, N., Ardila, D. R., Bartko, F., Bouwens, R. J., Bradley, L. D., , Broadhurst, T. J., et al. (2005). The morphology-density relation in z ∼ 1 clusters. Astrophysical Journal Letters, 623(2 I), 721-741.
  More info

  Abstract: We measure the morphology-density relation (MDR) and morphology-radius relation (MRR) for galaxies in seven z ∼ 1 clusters that have been observed with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope. Simulations and independent comparisons of our visually derived morphologies indicate that ACS allows one to distinguish between E, S0, and spiral morphologies down to z8550 = 24, corresponding to L/L* = 0.21 and 0.30 at z = 0.83 and 1.24, respectively. We adopt density and radius estimation methods that match those used at lower redshift in order to study the evolution of the MDR and MRR. We detect a change in the MDR between 0.8 < z < 1.2 and that observed at z ∼ 0, consistent with recent work; specifically, the growth in the bulge-dominated galaxy fraction, f E+S0, with increasing density proceeds less rapidly at z ∼ 1 than it does at z ∼ 0. At z ∼ 1 and Σ ≥ 500 galaxies Mpc -2, we find 〈fE+S0〉 = 0-72 ± 0.10. At z ∼ 0, an E+S0 population fraction of this magnitude occurs at densities about 5 times smaller. The evolution in the MDR is confined to densities Σ ≳ 40 galaxies Mpc-2 and appears to be primarily due to a deficit of SO galaxies and an excess of Sp+Irr galaxies relative to the local galaxy population. Theye-density relation exhibits no significant evolution between z = 1 and 0. We find mild evidence to suggest that the MDR is dependent on the bolometric X-ray luminosity of the intracluster medium. Implications for the evolution of the disk galaxy population in dense regions are discussed in the context of these observations. © 2005. The American Astronomical Society. All rights reserved.
• Zirm, A. W., Overzier, R. A., Miley, G. K., Blakeslee, J. P., Clampin, M., Breuck, C. D., Demarco, R., Ford, H. C., Hartig, G. F., Homeier, N., Illingworth, G. D., Martel, A. R., Röttgering, H., Venemans, B., Ardila, D. R., Bartko, F., Benítez, N., Bouwens, R. J., Bradley, L. D., , Broadhurst, T. J., et al. (2005). Feedback and brightest cluster galaxy formation: ACS observations of the radio galaxy TN J1338-1942 at z = 4.1. Astrophysical Journal Letters, 630(1 I), 68-81.
  More info

  Abstract: We present deep optical imaging of the z = 4.1 radio galaxy TN J1338-1942, obtained using the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope, as well as ground-based near-infrared imaging data from the European Southern Observatory (ESO) Very Large Telescope (VLT). The radio galaxy is known to reside within a large galaxy overdensity (both in physical extent and density contrast). There is good evidence that this "protocluster" region is the progenitor of a present-day rich galaxy cluster. TN J1338 is the dominant galaxy in the protocluster in terms of size and luminosity (in both the optical and near-infrared) and therefore seems destined to evolve into the brightest cluster galaxy. The high spatial resolution ACS images reveal several kiloparsec-scale features within and around the radio galaxy. The continuum light is aligned with the radio axis and is resolved into two clumps in the i775 and z850 bands. These components have luminosities ∼109 L⊙ and sizes of a few kpc. The estimated nebular continuum, scattered light, synchrotron- and inverse Compton-scattering contributions to the aligned continuum light are only a few percent of the observed total, indicating that the observed flux is likely dominated by forming stars. The estimated star formation rate for the whole radio galaxy is ∼200 M⊙ yr-1. A simple model in which the jet has triggered star formation in these continuum knots is consistent with the available data. A striking, but small, linear feature is evident in the z850 aligned light and may be indicative of a large-scale shock associated with the advance of the radio jet. The rest of the aligned light also seems morphologically consistent with star formation induced by shocks associated with the radio source, as seen in other high-z radio galaxies (e.g., 4C 41.17). An unusual feature is seen in Lya emission. A wedge-shaped extension emanates from the radio galaxy perpendicularly to the radio axis. This "wedge" naturally connects to the surrounding asymmetric, large-scale (∼ 100 kpc) Lyα halo. We posit that the wedge is a starburst-driven superwind associated with the first major epoch of formation of the brightest cluster galaxy. The shock and wedge are examples of feedback processes due to both active galactic nucleus and star formation in the earliest stages of massive galaxy formation. © 2005. The American Astronomical Society. All rights reserved.
• Bartko, F., Zirm, A., Zheng, W., White, R. L., Tsvetanov, Z. I., Tran, H. D., Sparks, W. B., Sirianni, M., Rosati, P., Postman, M., Overzier, R., Miley, G. K., Meurer, G. R., Menanteau, F., Martel, A. R., Lesser, M. P., Krist, J. E., Kimble, R. A., Infante, L., , Illingworth, G. D., et al. (2004). THE LUMINOSITY FUNCTION OF EARLY-TYPE FIELD GALAXIES AT Z 0.75. The Astronomical Journal, 128(5), 1990-2012. doi:10.1086/424857
  More info

  We measure the luminosity function of morphologically selected E/S0 galaxies from z = 0.5 to 1.0 using deep high-resolution Advanced Camera for Surveys (ACS) imaging data. Our analysis covers an area of 48 arcmin2 (8 times the area of the Hubble Deep Field North) and extends 2 mag deeper (I ~ 24 mag) than was possible in the Deep Groth Strip Survey (DGSS). Our fields were observed as part of the ACS Guaranteed Time Observations. At 0.5 1.7, E/S0 galaxies at brighter luminosities (MB < -20.1), but are increasingly different at fainter magnitudes, where blue galaxies are both smaller and have lower Sersic parameters. We find differences in both the size-magnitude relation and the photometric plane offset for red and blue E/S0s, although neither red nor blue galaxies give a good fit to the size-magnitude relation. Fits of the colors to stellar population models suggest that most E/S0 galaxies have short star formation timescales (? < 1 Gyr), and that galaxies have formed at an increasing rate from z ~ 8 until z ~ 2, after which there has been a gradual decline.
• Benítez, N., Ford, H., Bouwens, R., Menanteau, F., Blakeslee, J., Gronwall, C., Illingworth, G., Meurer, G., Broadhurst, T. J., Clampin, M., Franx, M., Hartig, G. F., Magee, D., Sirianni, M., Ardila, D. R., Bartko, F., Brown, R. A., Burrows, C. J., Cheng, E. S., , Cross, N. J., et al. (2004). Faint galaxies in deep advanced camera for surveys observations. Astrophysical Journal, Supplement Series, 150(1), 1-18.
  More info

  Abstract: We present the analysis of the faint galaxy population in the Advanced Camera for Surveys (ACS) Early Release Observation fields VV 29 (UGC 10214) and NGC 4676. These observations cover a total area of 26.3 arcmin 2 and have depths close to that of the Hubble Deep Fields in the deepest part of the VV 29 image, with 10 σ detection limits for point sources of 27.8, 27.6, and 27.2 AB magnitudes in the g F475W, V F606W, and I F814W bands, respectively. Measuring the faint galaxy number count distribution is a difficult task, with different groups arriving at widely varying results even on the same data set. Here we attempt to thoroughly consider all aspects relevant for faint galaxy counting and photometry, developing methods that are based on public software and that are easily reproducible by other astronomers. Using simulations we determine the best SExtractor parameters for the detection of faint galaxies in deep Hubble Space Telescope observations, paying special attention to the issue of deblending, which significantly affects the normalization and shape of the number count distribution. We confirm, as claimed by Bernstein, Freedman, & Madore, that Kron-like magnitudes, such as the ones generated by SExtractor, can miss more than half of the light of faint galaxies, what dramatically affects the slope of the number counts. We show how to correct for this effect, which depends sensitively not only on the characteristics of the observations, but also on the choice of SExtractor parameters. We present catalogs for the VV 29 and NGC 4676 fields with photometry in the F475W, F606W, and F814W bands. We also show that combining the Bayesian software BPZ with superb ACS data and new spectral templates enables us to estimate reliable photometric redshifts for a significant fraction of galaxies with as few as three filters. After correcting for selection effects, we measure slopes of 0.32 ± 0.01 for 22 < g F475W < 28, 0.34 ± 0.01 for 22 < V F606W < 27.5, and 0.33 ± 0.01 for 22 < m F814W < 27. The counts do not flatten (except perhaps in the F475W filter), up to the depth of our observations. Our results agree well with those of Bernstein, Freedman, & Madore, who used different data sets and techniques, and show that it is possible to perform consistent measurements of galaxy number counts if the selection effects are properly considered. We find that the faint counts m AB > 25.5 can be well approximated in all our filters by a passive luminosity evolution model based on the COMBO-17 luminosity function (α = -1.5), with a strong merging rate following the prescription of Glazebrook et al., φ* ∝ (1 + Qz), with Q = 4.
• Burke, B. E., Gregory, J. A., Loomis, A. H., Lesser, M., Bautz, M. W., Kissel, S. E., Rathman, D. D., III, R. O., Cooper, M. J., Lind, T. A., & Ricker, G. R. (2004). CCD soft-X-ray detectors with improved high- and low-energy performance. IEEE Transactions on Nuclear Science, 51(5 I), 2322-2327.
  More info

  Abstract: We describe results from recent enhancements to the performance of charge-coupled devices (CCDs) to both low- and high-energy soft X-rays. For improved low-energy (E < 500 eV) sensitivity, we show that a low-temperature surface treatment on back-illuminated devices results in superior energy resolution compared to that of the devices flown on Chandra, which had a more process-intensive, high-temperature treatment. For improved high-energy response, we describe a design approach for MOS CCDs that allows high substrate biases for deep depletion (up to 160 μm) and, thus, improved X-ray detection for E > 5 keV.
• Burke, B., Tonry, J., Cooper, M., Luppino, G., Jacoby, G., Bredthauer, R., Boggs, K., Lesser, M., Onaka, P., Young, D., Doherty, P., & Craig, D. (2004). The orthogonal-transfer array: A new CCD architecture for astronomy. Proceedings of SPIE - The International Society for Optical Engineering, 5499, 185-192.
  More info

  Abstract: The orthogonal-transfer array (OTA) is a new CCD architecture designed to provide wide-field tip-tilt correction of astronomical images. The device consists of an 8×8 array of small (∼500×500 pixels) orthogonal-transfer CCDs (OTCCD) with independent addressing and readout of each OTCCD. This approach enables an optimum tip-tilt correction to be applied independently to each OTCCD across the focal plane. The first design of this device has been carried out at MIT Lincoln Laboratory in support of the Pan-STARRS program with a collaborative parallel effort at Semiconductor Technology Associates (STA) for the WIYN Observatory. The two versions of this device are functionally compatible and share a common pinout and package. The first wafer lots are complete at Lincoln and at Dalsa and are undergoing wafer probing.
• Cross, N. J., Bouwens, R. J., Benítez, N., Blakeslee, J. P., Menanteau, F., Ford, H. C., Goto, T., Holden, B., Martel, A. R., Zirm, A., Overzier, R., Gronwall, C., Homeier, N., Clampin, M., Hartig, G. F., Illingworth, G. D., Ardila, D. R., Bartko, F., Broadhurst, T. J., , Brown, R. A., et al. (2004). The luminosity function of early-type field galaxies at z ≈ 0.75. Astronomical Journal, 128(5), 1990-2012.
  More info

  Abstract: We measure the luminosity function of morphologically selected E/S0 galaxies from z = 0.5 to 1.0 using deep high-resolution Advanced Camera for Surveys (ACS) imaging data. Our analysis covers an area of 48 arcmin 2 (8 times the area of the Hubble Deep Field North) and extends 2 mag deeper (I ∼ 24 mag) than was possible in the Deep Groth Strip Survey (DGSS). Our fields were observed as part of the ACS Guaranteed Time Observations. At 0.5 < z < 0.75, we find M B* - 5 log h 0.7 = -21.1 ± 0.3 and α = -0.53 ± 0.2, and at 0.75 < z < 1.0, we find M B* - 5 log h 0.7 = -21.4 ± 0.2, consistent with 0.3 mag of luminosity evolution (across our two redshift intervals). These luminosity functions are similar in both shape and number density to the luminosity function using morphological selection (e.g., DGSS), but are much steeper than the luminosity functions of samples selected using morphological proxies such as the color or spectral energy distribution (e.g., CFRS, CADIS, or COMBO-17). The difference is due to the "blue," (U -V) 0 < 1.7, E/S0 galaxies, which make up to ∼30% of the sample at all magnitudes and an increasing proportion of faint galaxies. We thereby demonstrate the need for both morphological and structural information to constrain the evolution of galaxies. We find that the blue E/S0 galaxies have the same average sizes and Sersic parameters as the "red," (U - V) 0 > 1.7, E/S0 galaxies at brighter luminosities (M B < -20.1), but are increasingly different at fainter magnitudes, where blue galaxies are both smaller and have lower Sersic parameters. We find differences in both the size-magnitude relation and the photometric plane offset for red and blue E/S0s, although neither red nor blue galaxies give a good fit to the size-magnitude relation. Fits of the colors to stellar population models suggest that most E/S0 galaxies have short star formation timescales (τ < 1 Gyr), and that galaxies have formed at an increasing rate from z ∼ 8 until z ∼ 2, after which there has been a gradual decline.
• Lesser, M. (2004). 4k×4k detectors for astronomy. Proceedings of SPIE - The International Society for Optical Engineering, 5499, 131-139.
  More info

  Abstract: Large format imaging detectors are required in many modern astronomical optical systems. With the increase in aperture size of large telescopes, the associated cameras for imaging and spectroscopy are much larger than those of a decade ago. Large physical format detectors are required to make full use of these cameras. The detector of choice has been the charge coupled devices (CCDs), although large format 4k×4k CMOS imagers have also been fabricated. We discuss recent developments in 4k×4k pixel imagers, typically with 15 micron pixels, which are over 60 mm per side. Several companies have produced such devices with the characteristics required for astronomy. Backside processing issues are discussed, including results from optimization efforts at the University of Arizona Imaging Technology Laboratory. We also discuss the use of such imagers in the 8k×8k 90Prime prime focus mosaic camera now in operation at the Steward Observatory 2.3 m telescope.
• Levay, Z., Bartko, F., Zheng, W., White, R. L., Tsvetanov, Z. I., Tran, H. D., Sparks, W. B., Sirianni, M., Rosati, P., Postman, M., Miley, G. K., Meurer, G. R., Menanteau, F., Martel, A. R., Magee, D., Levay, Z. G., Lesser, M. P., Krist, J. E., Kimble, R. A., , Infante, L., et al. (2004). FAINT GALAXIES IN DEEP ADVANCED CAMERA FOR SURVEYS OBSERVATIONS. Astrophysical Journal Supplement Series, 150(1), 1-18. doi:10.1086/380120
  More info

  We present the analysis of the faint galaxy population in the Advanced Camera for Surveys (ACS) Early Release Observation fields VV 29 (UGC 10214) and NGC 4676. These observations cover a total area of 26.3 arcmin 2 and have depths close to that of the Hubble Deep Fields in the deepest part of the VV 29 image, with 10 � detection limits for point sources of 27.8, 27.6, and 27.2 AB magnitudes in the g F475W , VF606W ,a ndIF814W bands, respectively. Measuring the faint galaxy number count distribution is a difficult task, with different groups arriving at widely varying results even on the same data set. Here we attempt to thoroughly consider all aspects relevant for faint galaxy counting and photometry, developing methods that are based on public software and that are easily reproducible by other astronomers. Using simulations we determine the best SExtractor parameters for the detection of faint galaxies in deep Hubble Space Telescope observations, paying special attention to the issue of deblending, which significantly affects the normalization and shape of the number count distribution. We confirm, as claimed by Bernstein, Freedman, & Madore, that Kron-like magnitudes, such as the ones generated by SExtractor, can miss more than half of the light offaint galaxies, what dramatically affects the slope of the number counts. We show how to correct for this effect, which depends sensitively not only on the characteristics of the observations, but also on the choice of SExtractor parameters. We present catalogs for the VV 29 and NGC 4676 fields with photometry in the F475W, F606W, and F814W bands. We also show that combining the Bayesian software BPZ with superb ACS data and new spectral templates enables us to estimate reliable photometric redshifts for a significant fraction of galaxies with as few as three filters. After correcting for selection effects, we measure slopes of 0:32 � 0:01for 22 25:5 can be well approximated in all our filters by a passive luminosity evolution model based on the COMBO-17 luminosity function (� ¼� 1:5), with a strong merging rate following the prescription of
• Menanteau, F., Ford, H. C., Illingworth, G. D., Sirianni, M., Blakeslee, J. P., Meurer, G. R., Martel, A. R., Benítez, N., Postman, M., Franx, M., Ardila, D. R., Bartko, F., Bouwens, R. J., Broadhurst, T. J., Brown, R. A., Burrows, C. J., Cheng, E. S., Clampin, M., Cross, N. J., , Feldman, P. D., et al. (2004). Internal color properties of resolved spheroids in the deep Hubble Space Telescope Advanced Camera for Surveys field of UGC 10214. Astrophysical Journal Letters, 612(1 I), 202-214.
  More info

  Abstract: We study the internal color properties of a morphologically selected sample of spheroidal galaxies taken from the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Early Release Observation program of UGC 10214 ("the Tadpole"). By taking advantage of the unprecedented high resolution of the ACS in this very deep data set, we are able to characterize spheroids at subarcsecond scales. Using the V606 and I814 bands, we construct V - I color maps and extract color gradients for a sample of spheroids at I814 < 24 mag. We assess the ability of the ACS to make resolved color studies of galaxies by comparing its results with the multicolor data from the Hubble Deep Fields (HDFs). Here we report that with ACS WFC data using less than ∼1/10 the exposure of the WFPC2 HDFs, it is possible to confidently carry out resolved studies of faint galaxies at similar magnitude limits. We also investigate the existence of a population of morphologically classified spheroids that show extreme variation in their internal color properties, similar to the ones reported in the HDFs. These are displayed as blue cores and inverse color gradients with respect to those accounted for from metallicity variations. Following the same analysis, we find a similar fraction of early-type systems (∼30%-40%) that show nonhomologous internal colors, suggestive of recent star formation activity. We present two statistics for quantifying the internal color variation in galaxies and tracing blue cores, from which we estimate the ratio of nonhomogeneous to homogeneous internal colors as a function of redshift up to z ≲ 1.2. We find that it can be described as about constant as a function of redshift, with a small increase with redshift for the fraction of spheroids that present strong color dispersions. The implications of a constant fraction at all redshifts suggests the existence of a relatively permanent population of evolving spheroids up to z ≲ 1. We discuss the implications of this in the context of spheroidal formation.
• Mieske, S., Infante, L., Benítez, N., Coe, D., Blakeslee, J. P., Zekser, K., Ford, H. C., Broadhurst, T. J., Illingworth, G. D., Hartig, G. F., Clampin, M., Ardila, D. R., Bartko, F., Bouwens, R. J., Brown, R. A., Burrows, C. J., Cheng, E. S., Cross, N. J., Feldman, P. D., , Franx, M., et al. (2004). Ultracompact dwarf galaxies in Abell 1689: A photometric study with the advanced camera for surveys. Astronomical Journal, 128(4), 1529-1540.
  More info

  Abstract: The properties of ultracompact dwarf (UCD) galaxy candidates in Abell 1689 (z = 0.183) are investigated, based on deep high-resolution images from the Hubble Space Telescope Advanced Camera for Surveys. A UCD candidate has to be unresolved, have i < 28 mag (MV < -11.5 mag), and satisfy color limits derived from Bayesian photometric redshifts. We find 160 UCD candidates with 22 mag < i < 28 mag. We estimate that about 100 of these are cluster members, based on their spatial distribution and photometric redshifts. For i ≲ 26.8 mag, the radial and luminosity distribution of the UCD candidates can be explained well by Abell 1689's globular cluster (GC) system. For i ≲ 26.8 mag, there is an overpopulation of 15 ± 5 UCD candidates with respect to the GC luminosity function. For i ≲ 26 mag, the radial distribution of UCD candidates is more consistent with the dwarf galaxy population than with the GC system of Abell 1689. The UCD candidates follow a color-magnitude trend with a slope similar to that of Abell 1689's genuine dwarf galaxy population, but shifted fainter by about 2-3 mag. Two of the three brightest UCD candidates (MV ≃ -17 mag) are slightly resolved. At the distance of Abell 1689, these two objects would have King profile core radii of ≃35 pc and reff ≃ 300 pc, implying luminosities and sizes 2-3 times those of M32's bulge. Additional photometric redshifts obtained with late-type stellar and elliptical galaxy templates support the assignment of these two resolved sources to Abell 1689 but also allow for up to four foreground stars among the six brightest UCD candidates. Our findings imply that in Abell 1689 there are ≥10 UCDs with MV < -12.7 mag, probably created by stripping "normal" dwarf or spiral galaxies. Compared with the UCDs in the Fornax Cluster - the location of their original discovery - they are brighter, larger, and have colors closer to normal dwarf galaxies. This suggests that they may be in an intermediate stage of the stripping process. Checking the photometric redshifts of the brightest UCD candidates with spectroscopy would be the next step to definitely confirm the existence of UCDs in Abell 1689.
• Williams, G. G., Olszewski, E. W., Lesser, M. P., & Burge, J. H. (2004). 90prime: A prime focus imager for the steward observatory 90-inch telescope. Proceedings of SPIE - The International Society for Optical Engineering, 5492(PART 2), 787-798.
  More info

  Abstract: Steward Observatory is currently commissioning a prime focus wide-field imager for the 90-inch telescope located at Kitt Peak. The camera's focal plane array is populated with a mosaic of four thinned Lockheed 4096 × 4096 pixel CCDs. The f/2.98 system provides a plate scale of 0.45″/pixel and a total field-of-view of 1.16° × 1.16°. The optical design includes a four element corrector and six position filter wheel. The first science run was conducted in November 2003. We will describe the design of the "90prime" instrument and results from the commissioning runs.
• Bouwens, R. J., Illingworth, G. D., Rosati, P., Lidman, C., Broadhurst, T., Franx, M., Ford, H. C., Magee, D., Benítez, N., Blakeslee, J. P., Meurer, G. R., Clampin, M., Hartig, G. F., Ardila, D. R., Bartko, F., Brown, R. A., Burrows, C. J., Cheng, E. S., Cross, N. J., , Feldman, P. D., et al. (2003). Star formation at z ∼ 6: i-dropouts in the advanced camera for surveys guaranteed time observation fields. Astrophysical Journal Letters, 595(2 I), 589-602.
  More info

  Abstract: Using an. i - z dropout criterion, we determine the space density of z ∼ 6 galaxies from two deep ACS GTO fields with deep optical-IR imaging. A total of 23 objects are found over 46 arcmin2, or ∼0.5 ± 0.1 objects arcmin-2 down to ZAB ∼ 27.3 (6 σ), or a completeness-corrected ∼0.5 ± 0.2 objects arcmin-2 down to ZAB ∼ 26.5 (including one probable z ∼ 6 active galactic nucleus). Combining deep ISAAC data for our RDCS 1252-2927 field (JAB ∼ 25.7 and KS,AB ∼ 25.0; 5 σ) and NICMOS data for the Hubble Deep Field-North (J110,AB and H 160,AB ∼ 27.3, 5 σ), we verify that these dropouts have relatively flat spectral slopes, as one would expect for star-forming objects at z ∼ 6. Compared with the average-color (β = -1.3) U-dropout in the Steidel et al. z ∼ 3 sample, i-dropouts in our sample range in luminosity from ∼1.5L* (zAB ∼ 25.6) to ∼0.3L* (z AB ∼ 27.3) with the exception of one very bright candidate at z850,AB ∼ 24.2. The half-light radii vary from 0.″09 to 0.″21, or 0.5 kpc to 1.3 kpc. We derive the z ∼ 6 rest-frame UV luminosity density (or star formation rate density) by using three different procedures. All three procedures use simulations based on a slightly lower redshift (z ∼ 5) V606-dropout sample from Chandra Deep Field-South ACS images. First, we make a direct comparison of our findings with a no-evolution projection of this V-dropout sample, allowing us to automatically correct for the light lost at faint magnitudes or lower surface brightnesses. We find 23% ± 25% more i-dropouts than we predict, consistent with no strong evolution over this redshift range. Adopting previous results to z ∼ 5, this works out to a mere 20% ± 29% drop in the luminosity density from z ∼ 3 to z ∼ 6. Second, we use the same V-dropout simulations to derive a detailed selection function for our i-dropout sample and compute the UV-luminosity density [(7.2 ± 2.5) × 10 25 ergs s-1 Hz-1 Mpc-3 down to zAB ∼ 27]. We find a 39% ± 21% drop over the same redshift range (z ∼ 3-6), consistent with the first estimate. This is our preferred value and suggests a star formation rate of 0.0090 ± 0.0031 M⊙ yr-1 Mpc-3 to zAB ∼ 27, or ∼0.036 ± 0.012 M⊙ yr-1 Mpc -3 by extrapolating the luminosity function to the faint limit, assuming α = - 1.6, Third, we follow a very similar procedure, except that we assume no incompleteness, and find a rest-frame continuum luminosity that is ∼2-3 times lower than our other two determinations. This final estimate is to be taken as a lower limit and is important if there are modest changes in the colors or surface brightnesses from z ∼ 5 to z ∼ 6 (the other estimates assume no large changes in the intrinsic select-ability of objects). We note that all three estimates are well within the canonical range of luminosity densities necessary for reionization of the universe at this epoch by star-forming galaxies.
• Burke, B. E., Gregory, J. A., Loomis, A. H., Lesser, M., Bautz, M. W., Kissel, S. E., Rathman, D. D., III, R. O., & Cooper, M. J. (2003). CCD soft-x-ray detectors with improved high- And low-energy performance. IEEE Nuclear Science Symposium Conference Record, 1, 355-359.
  More info

  Abstract: We describe results from recent efforts to enhance the performance of CCDs to both low- and high-energy soft x rays. For improved low-energy (E160 μm) and thus improved x-ray detection for E>5 keV.
• Clampin, M., Krist, J. E., Ardila, D. R., Golimowski, D. A., Hartig, G. F., Ford, H. C., Illingworth, G. D., Bartko, F., Benítez, N., Blakeslee, J. P., Bouwens, R. J., Broadhurst, T. J., Brown, R. A., Burrows, C. J., Cheng, E. S., Cross, N. J., Feldman, P. D., Franx, M., Gronwall, C., , Infante, L., et al. (2003). Hubble space telescope ACS coronagraphic imaging of the circumstellar disk around HD 141569A. Astronomical Journal, 126(1 1771), 385-392.
  More info

  Abstract: Multicolor coronagraphic images of the circumstellar disk around HD 141569A have been obtained with the Hubble Space Telescope Advanced Camera for Surveys. The B, V, and I images show that the disk's previously described multiple-ring structure is actually a continuous distribution of dust with a tightly wound spiral structure. Extending from the disk are two, more open spiral arms, one of which appears to reach the nearby binary star HD 141569BC. Diffuse dust is seen up to 1200 AU from HD 141569A. Although planets may exist in the inner region of the disk, tidal interaction with HD 141569BC seems more likely to be the cause of these phenomena. The disk appears redder than the star (B-V = 0.21 and V-I = 0.25), and its color is spatially uniform. A scattering asymmetry factor of g = 0.25-0.35 is derived. The azimuthal density distribution is asymmetric, varying by a factor of ∼3 at some radii.
• Martel, A. R., Ford, H. C., Tran, H. D., Illingworth, G. D., Krist, J. E., White, R. L., Sparks, W. B., Gronwall, C., Cross, N. J., Hartig, G. F., Clampin, M., Ardila, D. R., Bartko, F., Benítez, N., Blakeslee, J. P., Bouwens, R. J., Broadhurst, T. J., Brown, R. A., Burrows, C. J., , Cheng, E. S., et al. (2003). Coronagraphic imaging of 3C 273 with the advanced camera for surveys. Astronomical Journal, 125(6 1770), 2964-2974.
  More info

  Abstract: The nearby and luminous QSO 3C 273 was imaged in 2002 July with the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS) in coronagraphic mode in F475W (g), F606W (V), and F814W (I) as part of the Early Release Observations (ERO) program. After subtraction of the remaining PSF of the QSO, these images offer the most detailed view yet of the morphology and colors of the host galaxy of this QSO. We find that the central light distribution is elongated along the jet axis and its outer edge is delineated by an arc, centered on the jet at a radius of ∼2″.6 from the QSO and bluer than the surrounding galaxy. This system is embedded in an extended galactic halo. Compared with early-type galaxies of similar redshifts and luminosities, the light distribution of 3C 273 is flatter in the core, likely from suppression by dust, but similar in the outer halo. The QSO is displaced from the isophotal center of the galaxy by ∼1″.4. Previously known emission-line extensions are confirmed and new morphological features are identified, including a dramatic spiral-shaped plume, two faint filaments, a dust lane, and a knot along the jet axis. Part of the inner jet is unambiguously detected in all three bandpasses, and its morphology matches that of a MERLIN radio map. Different mechanisms that could explain the morphology of 3C 273 are considered, such as scattered QSO radiation, a face-on disk, and a merger event.
• Meurer, G. R., Blakeslee, J. P., Sirianni, M., Ford, H. C., Illingworth, G. D., Benítez, N., Clampin, M., Menanteau, F., Tran, H. D., Kimble, R. A., Hartig, G. F., Ardila, D. R., Bartko, F., Bouwens, R. J., Broadhurst, T. J., Brown, R. A., Burrows, C. J., Cheng, E. S., Cross, N. J., , Feldman, P. D., et al. (2003). The discovery of globular clusters in the protospiral galaxy NGC 2915: Implications for hierarchical galaxy evolution. Astrophysical Journal Letters, 599(2 II), L83-L86.
  More info

  Abstract: We have discovered three globular clusters beyond the Holmberg radius in Hubble Space Telescope Advanced Camera for Surveys images of the gas-rich dark matter-dominated blue compact dwarf galaxy NGC 2915. The clusters, all of which start to resolve into stars, have MV606 = -8.9 to -9.8 mag, significantly brighter than the peak of the luminosity function of Milky Way globular clusters. Their colors suggest a metallicity [Fe/H] ≈ -1.9 dex, typical of metal-poor Galactic globular clusters. The specific frequency of clusters is at a minimum normal, compared to spiral galaxies. However, since only a small portion of the system has been surveyed, it is more likely that the luminosity and mass normalized cluster content is higher, like that seen in elliptical galaxies and galaxy clusters. This suggests that NGC 2915 resembles a key phase in the early hierarchical assembly of galaxies - the epoch when much of the old stellar population has formed but little of the stellar disk. Depending on the subsequent interaction history, such systems could go on to build up larger elliptical galaxies, evolve into normal spirals, or in rare circumstances remain suspended in their development to become systems like NGC 2915.
• Reynolds, R. O., Lloyd-hart, M., Lesser, M. P., Kenworthy, M. A., & Ge, J. (2003). Progress toward science results with the ACES spectrograph. Astronomical Telescopes and Instrumentation, 4841(3), 1705-1714. doi:10.1117/12.461762
  More info

  The use of spectrographs with telescopes having high order adaptive optics (AO) systems offers the possibility of achieving near diffraction-limited spectral resolution on ground-based telescopes, as well as important advantages for instrument design. The small stellar image diameters obtained with adaptively corrected systems allow high resolution without a large loss of light at the spectrograph entrance slit, as well as greater spectral coverage per exposure. The adaptively corrected echelle spectrograph (ACES), designed at Steward Observatory for a spectral resolution R ≈ 200,000, couples the telescope pupil to the instrument with a 10 mm diameter near single-mode optical fiber. Initial observations at the 2.5m telescope on Mt. Wilson validated the concept of achieving high spectral resolution with an adaptively corrected telescope and fiber coupled spectrograph. However the transmission of multiple modes in the fiber lead to a wavelength-dependent variation in illumination that made flat fielding impossible. In this paper we describe instrument design improvements, the installation and testing of a new CCD detector, and testing aimed at understanding and eliminating the fiber-related transmission problems to permit science quality imaging.
• Sullivan, P. C., Sirianni, M., Schrein, R. J., Lesser, M., Kimble, R. A., Illingworth, G. D., Hartig, G. F., Golimowski, D. A., Ford, H. C., Clampin, M., Burmester, B., & Blouke, M. M. (2003). CCD detectors for the advanced camera for surveys. SPIE milestone series, 177, 441-446.
  More info

  The Advanced Camera for Surveys (ACS) is a third generation science instrument scheduled for installation into the Hubble Space Telescope (HST) during the servicing mission 3B scheduled for June 2001. The instrument has three different cameras, each of which is optimized for a specific set of science goals. The first, the Wide Field Camera, will be a high throughput, wide field optical and I-band optimized camera that is half-critically sampled at approximately 570 nm. The second, the High Resolution Channel (HRC) has a 26 inch by 29 inch field of view, it is optimized for the near- UV and is critically sampled at approximately 630 nm. The third camera, the Solar-Blind Camera is a far-UV, photon counting array that has a relatively high throughput over a 26 inch by 29 inch field of view. Two of the three cameras employ CCD detectors: the WFC a mosaic of two SITe 2048 by 4096 pixel CCDs and the HRC a 1024 by 1024 CCD based on the Space Telescope Imaging Spectrograph 21 micrometers pixel CCD. IN this paper we review the performances of the devices baselined as flight candidates.
• Tran, H. D., Sirianni, M., Ford, H. C., Illingworth, G. D., Clampin, M., Hartig, G., Becker, R. H., White, R. L., Bartko, F., Benítez, N., Blakeslee, J. P., Bouwens, R., Broadhurst, T. J., Brown, R., Burrows, C., Cheng, E., Cross, N., Feldman, P. D., Franx, M., , Golimowski, D. A., et al. (2003). Advanced camera for surveys observations of young star clusters in the interacting galaxy UGC 10214. Astrophysical Journal Letters, 585(2 I), 750-755.
  More info

  Abstract: We present the first Advanced Camera for Surveys (ACS) observations of young star clusters in the colliding/merging galaxy UGC 10214. The observations were made as part of the Early Release Observation (ERO) program for the newly installed ACS during service mission SM3B for the Hubble Space Telescope (HST). Many young star clusters can be identified in the tails of UGC 10214, with ages ranging from ∼3 to 10 Myr. The extreme blue V-I(F606W-F814W) colors of the star clusters found in the tail of UGC 10214 can only be explained if strong emission lines are included with a young stellar population. This has been confirmed by our Keck spectroscopy of some of these bright blue stellar knots. The most luminous and largest of these blue knots has an absolute magnitude of Mv = - 14.45, with a half-light radius of 161 pc, and if it is a single star cluster, it would qualify as a super star cluster (SSC). Alternatively, it could be a superposition of multiple scaled OB associations or clusters. With an estimated age of ∼4-5 Myr, its derived mass is less than 1.3 × 106 M⊙. Thus, the young stellar knot is unbound and will not evolve into a normal globular cluster. The bright blue clusters and associations are much younger than the dynamical age of the tail, providing strong evidence that star formation occurs in the tail long after it was ejected. UGC 10214 provides a nearby example of processes that contributed to the formation of halos and intracluster media in the distant and younger universe.
• Woodruff, R. A., White, R. L., Volmer, P., Tsvetanov, Z. I., Tran, H. D., Sullivan, P. C., Sparks, W. B., Sirianni, M., Rosati, P., Rafal, M. D., Postman, M., Miley, G. K., Meurer, G. R., Mccann, W. J., Martel, A. R., Magee, D., Lesser, M. P., Krist, J. E., Kimble, R. A., , Illingworth, G. D., et al. (2003). Overview of the Advanced Camera for Surveys on-orbit performance. Astronomical Telescopes and Instrumentation, 4854, 81-94. doi:10.1117/12.460040
  More info

  We present an overview of the ACS on-orbit performance based on the calibration observations taken during the first three months of ACS operations. The ACS meets or exceeds all of its important performance specifications. The WFC and HRC FWHM and 50% encircled energy diameters at 555 nm are 0.088" and 0.14", and 0.050" and 0.10". The average rms WFC and HRC read noises are 5.0 e- and 4.7 e-. The WFC and HRC average dark currents are ~ 7.5 and ~ 9.1 e-/pixel/hour at their operating temperatures of - 76°C and - 80°C. The SBC + HST throughput is 0.0476 and 0.0292 through the F125LP and F150LP filters. The lower than expected SBC operating temperature of 15 to 27°C gives a dark current of 0.038 e-/pix/hour. The SBC just misses its image specification with an observed 50% encircled energy diameter of 0.24" at 121.6 nm. The ACS HRC coronagraph provides a 6 to 16 direct reduction of a stellar PSF, and a ~1000 to ~9000 PSF-subtracted reduction, depending on the size of the coronagraphic spot and the wavelength. The ACS grism has a position dependent dispersion with an average value of 3.95 nm/pixel. The average resolution λ/Δλ for stellar sources is 65, 87, and 78 at wavelengths of 594 nm, 802 nm, and 978 nm.
• Ay, S. U., Lesser, M., & Fossum, E. R. (2002). CMOS Active Pixel Sensor (APS) imager for scientific applications. Proceedings of SPIE - The International Society for Optical Engineering, 4836, 271-278.
  More info

  Abstract: A 512×512 CMOS Active Pixel Sensor (APS) imager has been designed, fabricate, and tested for frontside illumination suitable for use in astronomy specifically in telescope guider systems as a replacement of CCD chips. The imager features a high-speed differential analog readout, 15 μm pixel pitch, 75% fill factor (FF), 62 dB dynamic range, 315Ke- pixel capacity, less than 0.25% fixed pattern noise (FPN), 45 dB signal to noise ratio (SNR) and frame rate of up to 40 FPS. Design was implemented in a standard 0.5 μm CMOS process technology consuming less than 200 mWatts on a single 5 Volt power supply. CMOS Active Pixel Sensor (APS) imager was developed with pixel structure suitable for both frontside and backside illumination holding large number of electron in relatively small pixel pitch of 15 μm. High-speed readout and signal processing circuits were designed to achieve low fixed pattern noise (FPN) and nonuniformity to provide CCD-like analog outputs. Target spectrum range of operation for the imager is in near ultraviolet (300-400 nm) with high quantum efficiency. This device is going to be used as a test vehicle to develop backside-thinning process.
• Ford, H., Clampin, M., Hartig, G., Illingworth, G., Sirianni, M., Martel, A., Meurer, G., McCann, W. J., Sullivan, P., Bartko, F., Benitez, N., Blakeslee, J., Bouwens, R., Broadhurst, T., Brown, R., Burrows, C., Campbell, D., Cheng, E., Feldman, P., , Franx, M., et al. (2002). Overview of the advanced camera for surveys on-orbit performance. Proceedings of SPIE - The International Society for Optical Engineering, 4854, 81-94.
  More info

  Abstract: We present an overview of the ACS on-orbit performance based on the calibration observations taken during the first three months of ACS operations. The ACS meets or exceeds all of its important performance specifications. The WFC and HRC FWHM and 50% encircled energy diameters at 555 nm are 0.088 inches and 0.14 inches, and 0.050 inches and 0.10 inches. The average rms WFC and HRC read noises are 5.0 e- and 4.7 e-. The WFC and HRC average dark currents are ∼ 7.5 and ∼ 9.1 e-/pixel/hour at their operating temperatures of - 76°C and - 80°C. The SBC + HST throughput is 0.0476 and 0.0292 through the F125LP and F150LP filters. The lower than expected SBC operating temperature of 15 to 27°C gives a dark current of 0.038 e-/pix/hour. The SBC just misses its image specification with an observed 50% encircled energy diameter of 0.24 inches at 121.6 nm. The ACS HRC coronagraph provides a 6 to 16 direct reduction of a stellar PSF, and a ∼1000 to ∼9000 PSF-subtracted reduction, depending on the size of the coronagraphic spot and the wavelength. The ACS grism has a position dependent dispersion with an average value of 3.95 nm/pixel. The average resolution λ/Δλ for stellar sources is 65, 87, and 78 at wavelength of 594 nm, 802 nm, and 978 nm.
• Lesser, M. (2002). Very large format back illuminated CCDs. Experimental Astronomy, 14(2), 77-82.
  More info

  Abstract: The University of Arizona Imaging Technology Laboratoryhas processed several types of very large format (>4K × 4K pixel) charge coupled devices for low light level scientific applications. These back illuminated deviceswere produced from frontside die fabricated by or for Fairchild Imaging Systems, Semiconductor Technology Associates, the Jet Propulsion Laboratory, and Kodak. A Philips 7K × 9K frontside device has also been processed using similar techniques. The backside sensors yield >90% quantum efficiency (QE). All devices show excellent charge transfer efficiency (CTE > 0.999997) at operating temperatures (typically -100 °C). Devices specifically designed for low signal applications have been demonstrated with less than 4 electrons read noise. © 2003 Kluwer Academic Publishers.
• Lesser, M., & Tyson, T. (2002). Focal plane technologies for LSST. Proceedings of SPIE - The International Society for Optical Engineering, 4836, 240-246.
  More info

  Abstract: The baseline design for the Large Synoptic Survey Telescope (LSST) requires a detector mosaic of over 2 Gigapixels covering a 55 cm diameter focal plane with 0.2 arcsec sampling. The camera and detector package for this telescope will benefit greatly by utilizing advanced concepts not normally required for astronomical telescope instrumentation. For the detector assembly, these concepts include low-cost, back illuminated CMOS or CCDs detectors with integrated electronic modules, curved detectors which would allow fewer but larger individual sensors, small pixels which maintain high MTF and full well capacity, anti-blooming techniques, fully-buttable packaging, and near room temperature operation. The camera may require a low thermal conductance gas-filled dewar to reduce atmosphere loading on the window, interchangeable and compact optical filters, and a flexible internal shutter. In this paper we discuss these issues relating to LSST focal plane technology.
• Reynolds, R. O., Lloyd-Hart, M., Lesser, M. P., Kenworthy, M. A., & Jian, G. e. (2002). Progress toward science results with the ACES spectrograph. Proceedings of SPIE - The International Society for Optical Engineering, 4841(3), 1705-1714.
  More info

  Abstract: The use of spectrographs with telescopes having high order adaptive optics (AO) systems offers the possibility of achieving near diffraction-limited spectral resolution on ground-based telescopes, as well as important advantages for instrument design. The small stellar image diameters obtained with adaptively corrected systems allow high resolution without a large loss of light at the spectrograph entrance slit, as well as greater spectral coverage per exposure. The adaptively corrected echelle spectrograph (ACES), designed at Steward Observatory for a spectral resolution R ≈ 200,000, couples the telescope pupil to the instrument with a 10 μm diameter near single-mode optical fiber. Initial observations at the 2.5m telescope on Mt. Wilson validated the concept of achieving high spectral resolution with an adaptively corrected telescope and fiber coupled spectrograph. However the transmission of multiple modes in the fiber lead to a wavelength-dependent variation in illumination that made flat fielding impossible. In this paper we describe instrument design improvements, the installation and testing of a new CCD detector, and testing aimed at understanding and eliminating the fiber-related transmission problems to permit science quality imaging.
• Sirianni, M., Clampin, M., Hartig, G. F., Ford, H. C., Illingworth, G., Sullivan, P. C., Koldewyn, W., Burmester, B., Schrein, R. J., Albright, V., Lesser, M. P., & Blouke, M. M. (2002). Flight CCD detectors for the advanced camera for surveys. Proceedings of SPIE - The International Society for Optical Engineering, 4669, 202-206.
  More info

  Abstract: The Advanced Camera for Surveys (ACS) is a third generation science instrument scheduled for installation into the Hubble Space Telescope (HST) during the servicing mission 3B scheduled for late February 2002. The instrument has three cameras, each of which is optimized for a specific set of science goals. The first, the Wide Field Camera, is a high throughput (43% at 700 nm, including the HST OTA), wide field (200″×204″), optical and I-band optimized camera. The second, the High Resolution Channel (HRC) has a 26″×29″ field of view, it is optimized for the near-UV (a peak throughput of 24% at 500 nm) and is critically sampled at approximately 630 nm. The third camera, the Solar-Blind Camera is a far-UV, photon counting array that has a relatively high throughput over a 26″ × 29″ field of view. Two of the three cameras employ CCD detectors: the WFC a mosaic of two SITe 2048 × 4096 pixel CCDs and the HRC a 1024 × 1024 CCD based on the Space Telescope Imaging Spectrograph 21 micrometers pixel CCD. In this paper we review the performance of the flight detectors selected for ACS.
• Starr, B., Claver, C. F., Wolff, S., Tyson, J. A., Lesser, M., Daggert, L., Dominguez, R., Gomez, R., & Muller, G. (2002). The LSST instrument concept. Proceedings of SPIE - The International Society for Optical Engineering, 4836, 228-239.
  More info

  Abstract: The LSST Instrument is a wide-field optical (0.3 to lum) imager designed to provide a three degree field-of-view with better than 0.2 arcsecond sampling. The image surface of the LSST is approximately 55 cm in diameter with a curvature radius of 20 to 30 meters. The detector format is currently defined to be a circular mosaic of 568 2k × 2k devices faceted to synthesize this surface within the constraints of LSST's f/1.25 focal ratio. This camera will provide over 2.2 Gigapixels per image with a 2 second readout time. With an expected typical exposure time of as short as 10s, this will yield a nightly data set on order of 3 terapixels. The scale of the LSST Instrument is equivalent to a square mosaic of 47k × 47k. The LSST Instrument will also provide a filter mechanism, as well as optical shuttering capability. Imagers of this size pose interesting challenges in many design areas including detectors, interface electronics, data acquisition and processing pipelines, dewar construction, filter and shutter mechanisms. Further more, the LSST 3 mirror optical system places this instrument in a highly constrained volume where these challenges are compounded. Specific focus is being applied to meeting defined scientific performance requirements with an eye to total cost, system complexity, power consumption, reliability, and risk. This paper will describe the current efforts in the LSST Instrument Concept Design.
• Lesser, M., & Vu, P. (2001). Processing of back illuminated 4096×4096 Fairchild CCDs at the University of Arizona. Proceedings of SPIE - The International Society for Optical Engineering, 4306, 196-204.
  More info

  Abstract: The University of Arizona Imaging Technology Laboratory has processed 4096×4096 15-micron Charge Coupled Devices (CCDs) fabricated at Lockheed Martin Fairchild Systems for back illuminated scientific applications. The devices have been optimized for astronomical observations in a direct imaging mode. Three types of back illuminated devices have been developed. The oldest devices are CCD4096JJ detectors which were custom fabricated for astronomical applications. The CCD485 devices are commercial sensors, originally fabricated for digital photography and medical applications. Because no frontside ground contact was included on either device, a backside contact was developed and applied as part of the backside processing. With this addition, very high quality back illuminated sensors have been developed. The CCD486 is a newer version of the 4k×4k CCD with low noise amplifiers and a backside contact. These sensors have now been produced back illuminated with >90% QE and read noise under 4 elec trons. The devices show CTE of >0.999998. Back illuminated versions CCDs have been fabricated with peak-valley flatness non-uniformity of less than 10 microns. A new epoxy underfill technique was developed to achieve this flatness and to avoid underfill voiding during epoxy application and curing. The new method applies a contact force on the CCD during the entire 48 hour cure cycle.
• Clampin, M., Ford, H., Bartko, F., Bely, P., Broadhurst, T., Burrows, C., Cheng, E., Crocker, J., Franx, M., Feldman, P., Golimowski, D., Hartig, G., Illingworth, G., Kimble, R., & Lesser, M. (2000). Advanced camera for surveys. Proceedings of SPIE - The International Society for Optical Engineering, 4013, 344-351.
  More info

  Abstract: The Advanced Camera for Surveys (ACS) is a third generation instrument for the Hubble Space Telescope (HST). It is currently planned for installation in HST during the fourth servicing mission in Summer 2001. The ACS will has three cameras. The first, the Wide Field Camera (WFC) is a high-throughput (approxmately 42% at 600 nm, including the HST OTA), wide field imaging camera optimized for the near-IR. WFC has a 202 inches×202 inches field of view with a plate scale of 0.05 inch/pixel, delivered by a mosaic of two 2048×4096 CCDs. The WFC is designed to achieve a factor of 10 increase in discovery efficiency at 800 nm, where discovery efficiency is defined as the product of field of view and instrument throughput. The second, the High Resolution Camera (HRC) is a near-UV optimized camera designed for critically sampled imaging in the visible, with the capability for high contrast, coronographic imaging. The HRC has a field of view of 26 inches×29 inches with a plate scale of 0.027 inch/pixel. The third camera is the Solar Blind Camera (SBC), which is optimized for far-UV imaging. The SBC has a field of view of 31 inches×35 inches with a plate scale of 0.032 inch/pixel. The ACS science team will employ approximately 60% of the dedicated GTO time to conducting a WFC deep survey of clusters of galaxies at intermediate redshift, mapping the large scale distribution of dark matter around low redshift clusters, and studying the nature of galaxies at z>4. HRC observations of a sample of early galaxies will be surveyed for nuclear disks, and combined with spectroscopic observations to measure central masses and determine if black holes are present. A novel polarimetric technique will be used to measure geometric distances to galaxies and provide an independent measure of Ho. The HRC coronograph will be used to conduct studies of dust disks around nearby stars and to search for planets.
• Lesser, M. (2000). CCD backside coatings optimized for 200-300 nm observations. Proceedings of SPIE - The International Society for Optical Engineering, 4139, 8-15.
  More info

  Abstract: The high QE and large variety of formats makes modern back illuminated Charge-coupled devices (CCDs) nearly ideal detectors for most scientific imaging applications. In the ultraviolet (UV), however, quantum efficiency (QE) instability with temperature and with environmental conditions has limited their widespread use, especially for space applications. We have developed several techniques to achieve stable and high QE in the 200-300 nm wavelength range with back illuminated CCDs fabricated by various manufacturers. In this paper we report peak QE of over 90% at 240 nm (uncorrected from quantum yield). We describe a series of tests which demonstrate stability of these devices with temperature, humidity, and UV illumination. These results are all based in the chemisorption backside coating processes developed at the Steward Observatory CCD Laboratory.
• Sirianni, M., Clampin, M., Hartig, G. F., Ford, H. C., Golimowski, D. A., Illingworth, G., Sullivan, P., Blouke, M., Lesser, M., Burmester, B., Schrein, R., & Kimble, R. (2000). CCD detectors for the advanced camera for surveys. Proceedings of SPIE - The International Society for Optical Engineering, 4008, I/-.
  More info

  Abstract: The Advanced Camera for Surveys (ACS) is a third generation science instrument scheduled for installation into the Hubble Space Telescope (HST) during the servicing mission 3B scheduled for June 2001. The instrument has three different cameras, each of which is optimized for a specific set of science goals. The first, the Wide Field Camera, will be a high throughput (approx. 44% at 700nm, including the HST OTA), wide field (202 inches × 202 inches) optical and I-band optimized camera that is half-critically sampled at approx. 570nm. The second, the High Resolution Channel (HRC) has a 26 inches × 29 inches field of view, it is optimized for the near-UV (approx. 24% at 2500 nm including the HST OTA) and is critically sampled at approx. 630 nm. The third camera, the Solar-Blind Camera (SBC) is a far-ultraviolet, photon counting array that has a relatively high throughput (approx. 6% at 121.6 nm) over a 26 inches × 29 inches field of view. Two of the three cameras employ CCD detectors: the WFC a mosaic of two SITe 2048×4096 pixel CCDs and the HRC a 1024×1024 CCD based on the Space Telescope Imaging Spectrograph (STIS) 21 μm pixel CCD. In this paper we review the performances of the devices baselined as flight candidates.
• Clampin, M., Hartig, G. F., Ford, H. C., Sirianni, M., Purdue, G., Walkowicz, L., Golimowski, D. A., Illingworth, G., Blouke, M., Lesser, M., Burmester, B., Kimble, R., Sullivan, P., & Krebs, C. (1998). CCD detectors for the advanced camera for surveys. Proceedings of SPIE - The International Society for Optical Engineering, 3356(1), 332-337.
  More info

  Abstract: The Advanced Camera for Surveys will be installed in the Hubble Space Telescope during the third Servicing Mission in May 2000. The ACS has three cameras, each of which is optimized for a specific set of science goals. The Wide Field Camera, is a high throughput (45% at 700 nm, including the HST OTA), wide field (200 inches×204 inches), optical and I-band camera that is half critically sampled at 500 nm. The High Resolution Camera (HRC) is optimized for the near-UV (24% at 250 nm including OTA), has a 26 inches×29 inches field of view and is critically sampled at 500 nm. The Solar-Blind Camera, is a far-UV, photon counting camera that has a relatively high throughput (6% at 121.6 nm) over a 26 inches×29 inches field of view. The WFC employs a mosaic of two SITe 2048×4096 CCDs with 15 μm pixels and a SITe backside treatment, while the HRC channel is designed around a 1024×1024 CCD with 21 μm pixels, and a near-UV backside treatment developed at the Steward Observatory. In this paper we review the performance of the devices currently selected for flight, and discuss the design of their flight packages.
• Feldman, P. D., Bartko, F., Woodruff, B., White, R. L., Tsvetanov, Z., Sparks, B., Rafal, M. D., Postman, M., Neff, S. G., Miley, G. K., Lesser, M., Lajeunesse, T., Krebs, C. A., Kimble, R. A., Illingworth, G. D., Hartig, G. F., Golimowski, D. A., Ford, H. C., Feldman, P. D., , Crocker, J. H., et al. (1998). The Advanced Camera for Surveys. Bulletin of the American Astronomical Society, 191.
• Ford, H., Bartko, F., Bely, P., Broadhurst, T., Burrows, C., Cheng, E., Clampin, M., Crocker, J., Feldman, P., Golimowski, D., Hartig, G., Illingworth, G., Kimble, R., Lesser, M., & Miley, G. (1998). Advanced Camera for the Hubble Space Telescope. Proceedings of SPIE - The International Society for Optical Engineering, 3356(1), 234-248.
  More info

  Abstract: The Advanced Camera for the Hubble Space Telescope has three cameras. The first, the Wide Field Camera, will be a high-throughput (44% at 600 nm, including the HST OTA), wide field (200″×204″), 4096×4096 pixel CCD optical and I-band camera that is half-critically sampled at 500 nm. The second, the High Resolution Camera (HRC), is a 1024×1024 pixel CCD camera that is critically sampled at 500 nm. The HRC has a 26″×29″ field of view and 29% throughput at 250 nm. The HRC optical path includes a coronagraph that will improve the HST contrast near bright objects by a factor of approximately 10 at 900 nm. The third camera, the Solar-Blind Camera, is a far-ultraviolet, pulse-counting array that has a relatively high throughput (6% at 121.6 nm) over a 26″×29″ field of view. The Advanced Camera for Surveys (ACS) will increase HST's capability for surveys and discovery by a factor of approximately 10 at 800 nm. The ACS science team will use approximately 60% of its dedicated time to make deep surveys of 15 clusters of galaxies at redshifts between 0.2 and 2. We will map the large-scale distribution of dark matter around two low redshift rich clusters and investigate the evolution of galaxies and clusters of galaxies between redshifts of 0.5 and 1. We will study young galaxies and clusters of galaxies in fields centered on high-redshift radio galaxies. HRC images of an unbiased sample of early-type galaxies will be searched for small (r to approximately 100 pc) nuclear disks; subsequent spectroscopic observations of the disks will be used to measure the central masses to determine if massive black holes are present. We will use the HRC coronagraph to take broad-band, narrow-band, and polarimetric images of quasars and BL Lacs at redshifts between 0.2 and 0.5. We will use a novel polarimetric technique to measure geometric distances to galaxies and provide independent measures of H0. The coronagraph will be used to search nearby stars for proto-planetary disks, brown dwarf companions, and planets.
• Lesser, M., & Iyer, V. (1998). Enhancing back illuminated performance of astronomical CCDs. Proceedings of SPIE - The International Society for Optical Engineering, 3355, 446-456.
  More info

  Abstract: Back illuminated CCDs have been the detectors of choice for most astronomical imagers and spectrographs during the past decade. In recent years, we have developed processes to improve the performance of these detectors. Recent work has resulted in improved absolute quantum efficiency (QE), QE stability with temperature, QE stability with environmental contamination, and enhanced near-IR response. We demonstrate that QE near 100% can be achieved which is stable against hydrogen, dewar outgassing, and water contamination. We show that QE decrease with temperature can be eliminated for blue/visible optimized CCDs using a backside passivation layer, and significantly reduced for UV optimized CCDs which require very thin backside films. We also show that a 20% QE increase at 900 nm can be obtained by coating the frontside of back illuminated CCDs with a reflective metal film, without increasing interference fringing.
• Sirianni, M., Clampin, M., Hartig, G. F., Rafal, M., Ford, H. C., Golimowski, D. A., Tremonti, C., Illingworth, G., Blouke, M., Lesser, M., Burmester, B., Kimble, R., Sullivan, P., Krebs, C., & Yagelowicz, J. (1998). Long wavelength scattered light halos in ACS CCDs. Proceedings of SPIE - The International Society for Optical Engineering, 3355, 608-612.
  More info

  Abstract: During the ground calibration of the Space Telescope Imaging Spectrograph (STIS) large scattered light haloes were identified in images of point sources and long slit spectral images at long wavelengths (>750 nm). The long wavelength scattering was traced to the SITe 1024×1024 CCD and its header package, raising concerns for the performance of the Advanced Camera for Surveys (ACS) CCD detectors. ACS is a third generation axial instrument for the Hubble Space Telescope (HST) and will be installed during the 1999 Servicing Mission. Two of the ACS imaging channels employ SITe CCDs, so the ACS team have conducted a study of the long-wavelength scattering, in collaboration with SITe, to assess the impact to the ACS science program and develop a solution. In this paper we discuss our solution, its implementation on ACS CCDs, and describe the results of initial tests.
• Ford, H., Bartko, F., Bely, P., Broadhurst, T., Burrows, C., Cheng, E., Clampin, M., Crocker, J., Feldman, P., Golimowski, D., Hartig, G., Illingworth, G., Kimble, R., Lesser, M., & Miley, G. (1997). Advanced camera for the Hubble Space Telescope. Space Congress Proceedings.
  More info

  Abstract: The key features of the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) are described. These features include a high throughput, wide field, optical and I-band camera, a critically sampled high resolution camera, and a high throughput, moderate field of view far ultraviolet, solar-blind camera. The performance of the ACS was also compared with that of the Wide Field and Planetary Camera (WFPC2) and the FOC.
• Lesser, M. P., & McCarthy, B. (1996). Quantum efficiency characterization of scientific CCDs. Proceedings of SPIE - The International Society for Optical Engineering, 2654, 278-286.
  More info

  Abstract: Characterization of CCDs is extremely important when developing scientific detectors. If CCD foundries are used to produce the devices, the foundries require feedback to maintain a quality process. In this case, the users require fairly automated testing to evaluate the large number of devices obtained from even a single lot run. We have developed a CCD characterization facility which is used to evaluate these foundry devices as well as commercial scientific images. Our test capabilities include automated QE measurements, X-ray CTE and gain calibration, optical illumination from 200 nm - 1200 nm, and dark current and read noise characterization. We can also make interferometric flatness measurements of the devices. A cryogenic probe station for wafer testing is being developed to extend some of these tests to the wafer level. We discuss in this paper our facilities and techniques to measure the quantum efficiency (QE) of scientific CCDs. QE (along with read noise) is perhaps the most important parameter for many classes of astronomical observations when working at very low light levels. It is also the most useful parameter for evaluating the quality of backside processing when developing back illuminated CCDs.
• Woodruff, R. A., White, R. L., Volmer, P., Tsvetanov, Z. I., Sullivan, P. C., Sparks, W. B., Slusher, R. B., Postman, M., Neff, S. G., Miley, G. H., Leviton, D. B., Lesser, M. P., Krebs, C. A., Kimble, R. A., Johnson, R., Jeunesse, T. L., Illingworth, G. D., Hartig, G. F., Golimowski, D. A., , Ford, H. C., et al. (1996). Advanced camera for the Hubble Space Telescope. Astronomical Telescopes and Instrumentation, 3356, 234-248. doi:10.1117/12.324464
  More info

  The Advanced Camera for the Hubble Space Telescope has three cameras. The first, the Wide Field Camera, will be a high- throughput, wide field, 4096 X 4096 pixel CCD optical and I-band camera that is half-critically sampled at 500 nm. The second, the High Resolution Camera (HRC), is a 1024 X 1024 pixel CCD camera that is critically sampled at 500 nm. The HRC has a 26 inch X 29 inch field of view and 29 percent throughput at 250 nm. The HRC optical path includes a coronagraph that will improve the HST contrast near bright objects by a factor of approximately 10 at 900 nm. The third camera, the solar-blind camera, is a far-UV, pulse-counting array that has a relatively high throughput over a 26 inch X 29 inch field of view. The advanced camera for surveys will increase HST's capability for surveys and discovery by a factor of approximately 10 at 800 nm.
• Lesser, M. P., & Ouellette, D. B. (1995). Back-illuminated CCD mosaics. Proceedings of SPIE - The International Society for Optical Engineering, 2415, 182-188.
  More info

  Abstract: One of the drawbacks of using charge-coupled devices (CCDs) for scientific imaging is their relatively small size compared to many optical systems in which they are used. Telescopes, large format cameras, and medical imaging often require detectors much larger than the few cm dimensions of modern CCDs. One solution to this problem is to closely butt several CCDs together in the focal plane of the optical system, creating a focal plane mosaic. We have developed techniques to produce back illuminated CCDs from commercial front illuminated devices for enhanced quantum efficiency and spectral coverage. In this paper we discuss our development of packages and packaging techniques to butt back illuminated CCDs together, creating mosaics of up to 64 million pixels. We have discovered several critical issues during our development of back illuminated edge-buttable CCDs which we discuss in this paper. These include the development of proper chip carriers and packages, the ability to uniformly heat the devices in the required oxidation process, the ability to uniformly match antireflection coatings for all devices in a mosaic, and the development of alternative bonding methods which allow easy bonding of edge-buttable CCDs, especially as they approach whole wafer size.
• Liebert, J., Schmidt, G. D., Lesser, M., Stepanian, J. A., Lipovetsky, V. A., Chaffee, F. H., Foltz, C. B., & Bergeron, P. (1994). Discovery of a dwarf carbon star with a white dwarf companion and of a highly magnetic degenerate star. Astrophysical Journal Letters, 421(2), 733-737.
  More info

  Abstract: We report herein the discovery of two very unusual stars, identified during follow-up spectroscopy of candidates from the Second Byurakan Survey (SBS). SBS 1517-1-5017 is an object with a composite spectrum which we identify as a dwarf carbon star plus white dwarf binary - only the second such combination known. Since the system is unresolved spatially, we cannot yet determine whether the separation is small enough for mass transfer to have occurred when the evolved component was an asymptotic giant. The second unusual object we examine is SBS 1349 + 5434, which we show to be a magnetic white dwarf with an equivalent polar field strength among the strongest found among white dwarfs at 760 × 106 G. Given its immense field, the low measured polarization - both linear and circular - of this object is surprising and suggests that the field pattern over the stellar surface may be quite complex.
• Paresce, F., Natuurwetenschappen, F. D., Miley, G. K., Macchetto, F. D., Lesser, M., Kudritzki, R., Illingworth, G. D., Huchra, J. P., Fosbury, R. A., Deharveng, J., Crocker, J. H., & Brown, R. A. (1993). An Advanced Camera for HST. Bulletin of the American Astronomical Society.
• Lesser, M. P. (1992). Array detectors in astronomy. Proceedings of SPIE - The International Society for Optical Engineering, 1439, 144-151.
  More info

  Abstract: Charge-coupled devices (CCDs) have become extremely important detectors for the entire astronomical community. We discuss their properties in relation to astronomical imaging and spectroscopy. We also consider some of the improvements we hope to see to further their use in astronomy and other scientific fields. These include larger area detectors and mosaics of detectors with flat and stable packaging, antireflection coatings on back illuminated devices, and extremely low read noise for spectroscopic applications. We discuss some of our research into these areas.
• Lesser, M. P. (1991). Back-illuminated large-format Loral CCDs. Proceedings of SPIE - The International Society for Optical Engineering, 1447, 177-182.
  More info

  Abstract: The authors use charge-coupled devices (CCDs) from a lot of Loral wafers containing 3072 × 1024 and 800 × 1200 pixel detectors. These CCDs were specifically designed for astronomical spectrographic applications with the intention of thinning them at Steward Observatory for backside illumination. The thinning procedure and how it relates to the packaging method developed to keep the devices flat for use in fast optical beams are described. Initial results with a new oxidation procedure to allow better backside charging is also described. This oxidation method is especially effective with biased gate-charging techniques which apply a voltage directly over the backside oxide.
• Lesser, M. P. (1990). Recent charge-coupled device optimization results at Steward Observatory. Proceedings of SPIE - The International Society for Optical Engineering, 1235 pt 1, 236-241.
  More info

  Abstract: Recent research efforts aimed at optimizing charge-coupled devices (CCDs) after their manufacture to achieve maximum quantum efficiency, wide spectral bandpass, and excellent cosmetics and surface flatness are discussed. We present results of a new acid thinning agitation technique which produces very uniform, high quality surfaces on large area square and rectangular CCDs and 4' silicon wafers for back illuminated operation. In particular we present thinning results of Ford Aerospace 2048×2048 pixel CCDs. A method of cleaning thinned CCDs before antireflection coating for increased QE is also discussed. The results of initial experiments with a new packaging method to mount thinned CCDs while maintaining a very flat imaging surface are presented. This bump bonding mounting technique increases yield due to reduced handling and robust packaging and is expandable to tightly packed large area focal plane mosaics.
• Lesser, M. P. (1990). Recent charge-coupled device optimization results at steward observatory. Proceedings of SPIE - The International Society for Optical Engineering, 1242, 164-169.
  More info

  Abstract: Recent research efforts aimed at optimizing charge-coupled devices (CCDs) after their manufacture to achieve maximum quantum efficiency, wide spectral bandpass, and excellent cosmetics and surface flatness are discussed. We present results of a new acid thinning agitation technique which produces very uniform, high quality surfaces on large area square and rectangular CCDs and 4' silicon wafers for back illuminated operation. In particular we present thinning results of Ford Aerospace 2048×2048 pixel CCDs. A method of cleaning thinned CCDs before antireflection coating for increased QE is also discussed. The results of initial experiments with a new packaging method to mount thinned CCDs while maintaining a very flat imaging surface are presented. This bump bonding mounting technique increases yield due to reduced handling and robust packaging and is expandable to tightly packed large area focal plane mosaics.
• Sabol, B. A., Atwood, B., Hill, J. M., Williams, J. T., Lesser, M. P., Byard, P. L., & Davison, W. B. (1990). Evaporative coating systems for very large astronomical mirrors. Proceedings of SPIE - The International Society for Optical Engineering, 1236 pt 2, 940-951.
  More info

  Abstract: The design of aluminization systems for the MMT Conversion 6.5 m mirror and the Columbus Project 8 m mirror has led us to reconsider many of the design issues and tradeoffs for such systems. Coating of the large honeycomb mirrors will be done in situ on the telescope with a portable bell jar forming the front half of a two-stage vacuum system. The mirror cell forms a 'dirty' vacuum behind the mirror to eliminate excess force on the glass. A multi-ring source geometry has been proposed to allow a 1.0 m spacing between the mirror surface and the sources thereby minimizing the size of the vacuum chamber. Evaporation source models have been developed to optimize the number of sources, ring spacing, and high incidence angle emission to achieve better than 5% rms deviation in coating thickness over the diameter. Code results are compared to empirical thickness profiles measured at the University of Arizona's (UA) Sunnyside 2.0 m coating facility. Cryoadsorption pumps are considered for reasons of economy, quality of vacuum, pumping speed, and reliability. The interaction of the cryopumps and getter pumping with the pumping/cleaning/deposition cycle is studied. Glow discharge cleaning is discussed and the results of deposition tests in 10-4 Torr residual argon are given. Electrical requirements are estimated and a novel tranformer design may decrease the current entering the chamber from 12,000 A to less than 600 A.
• Romanishin, W., Oegerle, W. R., Lesser, M. P., Hintzen, P., Hill, J. M., Eisenhamer, J. D., & Batuski, D. J. (1988). Peculiar velocities of cD galaxies - MX spectroscopy of Abell 1795. The Astrophysical Journal, 332(1), L23. doi:10.1086/185258
  More info

  Spectroscopic observations of galaxies in the Abell 1795 field have been obtained using the MX multiple-object spectrograph on the Steward Observatory 2.3 m telescope. Redshifts are presented for 46 galaxies, including 41 cluster members. It is found that the A1795 cD galaxy is not at rest in the cluster gravitational potential well; it has a peculiar radial velocity, cz, of 365 km/s, and the hypothesis that the mean cluster velocity is as large as the cD's velocity can be rejected at the 99.5 percent confidence level. This conclusion is supported by spectroscopic data for the cooling flow gas found in the central region of the cluster; this gas, except for the portion coincident with the cD nucleus, lies at the velocity derived for the cluster mean. It is suggested that current models of the formation of cD galaxies are unlikely to account for the large peculiar velocities of the cD galaxies in A1795 and A2670 unless substantial subclustering is still present. However, the available data show no evidence for velocity subclustering in either A1795 or A2670. 25 references.
• Lesser, M. (1987). ANTIREFLECTION COATINGS FOR SILICON CHARGE-COUPLED DEVICES.. Optical Engineering, 26(9), 911-915.
  More info

  Abstract: With the increasing use of charge-coupled devices for astronomical observations, it is vital to obtain the highest quantum efficiency possible due to the limited amount of observing time available on large telescopes. One method of increasing the response of back-illuminated CCDs is to apply antireflection coatings. Because silicon's index of refraction is extremely high in the ultraviolet, a gain of more than 100% in quantum efficiency can be achieved at a wavelength of 0. 37 mu m with the proper choice of dielectric thin-film materials. We present a study of materials suitable for silicon CCD antireflection coatings for use in the 0. 32 to 1. 0 mu m spectral range. Constraints on these materials, such as refractive index, absorption coefficient, application method, temperature requirements, internal stress, and radioactivity, are discussed. We find hafnium oxide, lead fluoride, and aluminum oxide to be among the most suitable thin-film materials available. We present a number of single- and multiple-layer antireflection coating designs optimized for CCDs, with emphasis on the blue and ultraviolet.
• Lesser, M. (1987). Antireflection Coatings For Silicon Charge-Coupled Devices. Optical Engineering, 26(9), 911-915. doi:10.1117/12.7974170
  More info

  With the increasing use of charge-coupled devices for astronomical observations, it is vital to obtain the highest quantum efficiency possible due to the limited amount of observing time available on large telescopes. One method of increasing the response of back-illuminated CCDs is to apply antireflection coatings. Because silicon's index of refraction is extremely high in the ultra-violet, a gain of more than 100% in quantum efficiency can be achieved at a wavelength of 0.37 Am with the proper choice of dielectric thin-film materials. We present a study of materials suitable for silicon CCD antireflection coatings for use in the 0.32 to 1.0 Am spectral range. Constraints on these materials, such as refractive index, absorption coefficient, application method, tempera-ture requirements, internal stress, and radioactivity, are discussed. We find hafnium oxide, lead fluoride, and aluminum oxide to be among the most suitable thin-film materials available. We also present a number of single- and multiple-layer antireflection coating designs optimized for CCDs, with particular emphasis on the blue and ultraviolet.
• Lesser, M. P., & Leach, R. W. (1987). IMPROVING THE BLUE AND UV RESPONSE OF SILICON CCD DETECTORS. Publications of the Astronomical Society of the Pacific, 99(617), 668-671. doi:10.1086/132031
  More info

  A UV flooding technique derived from original work at JPL which boosts the response of two TI CCDs to nearly reflection limited values in the blue and UV is discussed along with some theory concerning silicon surface charging. This technique produces a photometrically stable detector that is well suited for use with ground-based optical telescopes.
• Hill, J. M., & Lesser, M. P. (1986). DEPLOYMENT OF THE MX SPECTROMETER.. Proceedings of SPIE - The International Society for Optical Engineering, 627(pt 1), 303-320.
  More info

  Abstract: The MX Spectrometer is a remotely controlled multiple object fiber optic spectrometer head. Mobile fiber probes provide the capacity to obtain simultaneous spectra of many objects. Our experience with the Medusa aperture plate fiber optic spectrograph led us to design and build the MX with automated fiber positioning in the telescope focal plane. 32 stepper motor driven probes in a fisherman-around-the-pond arrangement position 64 fibers in the 45 arcminute field of the Steward Observatory 2. 3m telescope. An onboard Z-80 microprocessor interfaces to 64 intelligent stepper motor controllers. The intelligent controllers allow simultaneous motion of all the probes for rapid field alignment. All fibers can be moved from one target pattern to another in less than 90 seconds. Two arcsecond diameter fiber apertures can be moved in steps as small as 0. 1 arcseconds (10 microns). Probe collisions are prevented by software which maps the footprint of each probe in the focal plane.
• Lesser, M. P., & Jacoby, G. H. (1981). Distances to nearby galaxies derived from planetary nebulae. The Astronomical Journal, 86, 185-192. doi:10.1086/112872
• Perrenod, S. C., & Lesser, M. P. (1980). A REDSHIFT SURVEY OF A HIGH-MULTIPLICITY SUPERCLUSTER.. Publications of the Astronomical Society of the Pacific, 92(550), 764-767. doi:10.1086/130743
  More info

  Redshifts have been obtained for 26 galaxies in a high-multiplicity supercluster. The redshifts occur in three distinct groups, indicating that the apparent supercluster which is seen on the sky is actually composed of three separate low-multiplicity groups of clusters. Large voids are found between the three superclusters.

Proceedings Publications

• Douglas, E. S., Aldering, G., Allan, G. W., Anche, R., Angel, R., Ard, C. C., Chakrabarti, S., Close, L. M., Derby, K., Edelstein, J., & others, . (2023). Approaches to lowering the cost of large space telescopes. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV, 12677.
• Joshi, A., Chiaverini, D. J., Kashyap, S., Madhugiri, V., Patti, R., Hong, S., & Lesser, M. (2021). Novel 8-inch wafer scale process for low-cost production of back side illuminated (BSI) imaging sensors. In Image Sensing Technologies: Materials, Devices, Systems, and Applications VIII, 11723.
• Konidaris, N. P., Drory, N., Froning, C. S., Hebert, A., Bilgi, P., Blanc, G. A., Lanz, A. E., Hull, C. L., Kollmeier, J. A., Ramirez, S., & others, . (2020). SDSS-V local volume mapper instrument: pverview and status. In Ground-based and Airborne Instrumentation for Astronomy VIII, 11447.
• Harbeck, D. R., Lesser, M., Liu, W., Stupak, B., George, R., Harris, R., Poczulp, G., Rajagopal, J., Kotulla, R., Ouellete, D., Hooper, E. J., Smith, M., Mason, D., Onaka, P., Chin, G., Hunting, E., & Christensen, R. (2018, Jul). The WIYN one degree imager in 2018: an extended 30-detector focal plane. In Ground-based and Airborne Instrumentation for Astronomy VII, 10702.
• Harbeck, D. R., Boroson, T., Lesser, M., Rajagopal, J., Yeatts, A., Corson, C., Liu, W., Dell'Antonio, I., Kotulla, R., Ouellette, D., Hooper, E., Smith, M., Bredthauer, R., Martin, P., Muller, G., Knezek, P., & Hunten, M. (2014, jul). The WIYN one degree imager 2014: performance of the partially populated focal plane and instrument upgrade path. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 9147, 0.
• Tuttle, S. E., Hill, G. J., Lee, H., Vattiat, B., Noyola, E., Drory, N., Cornell, M., Peterson, T., Chonis, T., Allen, R., Dalton, G., DePoy, D., Edmonston, D., Fabricius, M., Haynes, D., Kelz, A., Landriau, M., Lesser, M., Leach, B., , Marshall, J., et al. (2014, jul). The construction, alignment, and installation of the VIRUS spectrograph. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 9147, 0.
• Vo, C. L., Tanaka, M., Takehara, K., Ouellette, D., Okinaka, T., Nguyen, D. H., Maruyama, H., Lesser, M., Kuijk, H. V., Klaassens, W., Hayashida, T., Etoh, T. G., Dao, S. V., Bosiers, J. T., & Arai, T. (2011). A 16 Mfps 165kpixel backside-illuminated CCD. In 2011 IEEE International Solid-State Circuits Conference, 406-408.
  More info

  In 2002, we reported a CCD image sensor with 260×312 pixels capable of capturing 103 consecutive images at 1,000,000 frames per second (1Mfps) [1]. We named the sensor “ISIS-V2”, for In-situStorage Image Sensor Version 2. 103 memory elements are attached to every pixel; generated image signals were instantly and continuously stored in the in-situstorage without being read out of the sensor. The ultimate high-speed recording was enabled by this parallel recording at all pixels. In 2006, the color version, ISIS-V4, was reported [2]. In 2009, we developed ISIS-V12, a backside-illuminated image sensor mounting the ISIS structure and the CCM, charge-carrier multiplication, on the front side [3]. The CCM is a CCD-specific efficient signal-amplification device. CCM, combined with the BSI structure and cooling, achieved very high sensitivity. The ISIS-V12 was a test sensor intended to prove the technical feasibility of the structure. The maximum frame rate was 250kfps for a charge-handling capacity of Q max =10,000e− and 1Mfps for a reduced Q max . The pixel count was 489×400 pixels. For backside-illuminated (BSI) image sensors, metal wires can be placed on the front surface to increase the frame rate without reducing fill factor or violating uniformity of the pixel configuration. It has been proved by simulations that 100Mfps is achievable by introducing innovative technologies including a special wiring method [4]. We now report on ISIS-V16, developed by incorporating technologies to increase the frame rate with those to achieve very high sensitivity, which was confirmed by evaluation of ISIS-V12. The performance specification of ISIS-V16 is summarized in Fig. 23.4.1.
• Vo-le, C., Tominaga, H., Takehara, K., Soya, H., Singh, S., Nguyen, H. D., Maruno, H., Lesser, M., Kuijk, H. V., Kondo, Y., Klaassens, W., Ingram, G., Etoh, T. G., Dao, V. T., & Bosiers, J. T. (2008). Evaluation of a backside-illuminated ISIS. In SPIE Proceedings, 7126.
  More info

  This paper presents preliminary evaluation results of a test sensor of the backside-illuminated ISIS, an ultra-high sensitivity and ultra-high speed CCD image sensor. To achieve ultra-high sensitivity, the CCD image sensor employs the following three technologies: backside illumination, cooling and Charge Carrier Multiplication (CCM). The test sensor has been designed, fabricated and evaluated. At room temperature without cooling, the video camera has about ten-time higher sensitivity than the previous one, which was supported by a conventional front side illumination technology. Furthermore, the video camera can detect images at very low signal level, less than 5 e-, by using CCM at -40 degree C.
• Cooper, M. J., Ricker, G. R., Rathman, D. D., Osgood, R. M., Loomis, A. H., Lind, T. A., Lesser, M., Kissel, S. E., Gregory, J. A., Gr, J. A., Cooper, M. J., Burke, B. E., & Bautz, M. W. (2003). CCD soft-X-ray detectors with improved high- and low-energy performance. In IEEE Transactions on Nuclear Science, 51, 2322-2327.
  More info

  We describe results from recent efforts to enhance the performance of CCDs to both low- and high-energy soft a rays. For improved low-energy (E 160 /spl mu/m) and thus improved x-ray detection for E>5 keV.
• Clamping, M., Ford, H. C., Bartko, F., Bely, P. Y., Broadhurst, T., Burrows, C., Cheng, E., Crocker, J., Franx, M., Feldman, P. D., Golimowski, D. A., Hartig, G. F., Illingworth, G. D., Kimble, R. A., Lesser, M. P., Lesser, M. P., Miley, G. H., Postman, M., Rafal, M. D., , Rosati, P., et al. (2000). The Advanced Camera for surveys. In Space Telescopes and Instruments V.
  More info

  The Advanced Camera for. Surveys (ACS) is a third generation instrument for the Hubble Space Telescope (HST). It is currently planned for installation in HST during the fourth servicing mission in Summer 2001. The ACS will has three cameras. The first, the Wide Field Camera (WFC) is a high-throughput (-42% at 600 nm, including the HST OTA), wide field imaging camera optimized for the near-IR. WFC has a 202 x 202 field of view with a plate scale of 0.05/pixel, delivered by a mosaic of two 2048 x 4096 CCDs. The WFC is designed to achieve a factor of 10 increase in discovery efficiency at 800 nm, where discovery efficiency is defined as the product of field of view and instrument throughput. The second, the High Resolution Camera (HRC) is a near-UV optimized camera designed for critically sampled imaging in the visible, with the capability for high contrast, coronographic imaging. The HRC has a field of view of 26 x 29 with a plate scale of 0.027/pixel. The third camera is the Solar Blind Camera (SBC), which is optimized for far-UV imaging. The SBC has a field of view of 31 x 35 with a plate scale of 0.032/pixel. The ACS science team will employ -60% of the dedicated GTO time to conducting a WFC deep survey of clusters of galaxies at intermediate redshift, mapping the large scale distribution of dark matter around low redshift clusters, and studying the nature of galaxies at z>4. HRC observations of a sample of early galaxies will be surveyed for nuclear disks, and combined with spectroscopic observations to measure central masses and determine if black holes are present. A novel polarimetric technique will be used to measure geometric distances to galaxies and provide an independent measure of Ho. The HRC coronograph will be used to conduct studies of dust disl around nearby stars and to search for planets.
• Lesser, M. P. (2000). CCD backside coatings optimized for 200- to 300-nm observations. In SPIE Proceedings, 4139, 8-15.
  More info

  The high QE and large variety of formats make modern back illuminated Charge-coupled devices (CCDs) nearly ideal detectors for most scientific imaging applications. In the ultraviolet (UV), however, quantum efficiency (QE) instability with temperature and with environmental conditions has limited their widespread use, especially for space applications. We have developed several techniques to achieve stable and high QE in the 200 - 300 nm wavelength range with back illuminated CCDs fabricated by various manufacturers. In this paper we report peak QE of over 90% at 240 nm (uncorrected from quantum yield). We describe a series of tests which demonstrate stability of these devices with temperature, humidity, and UV illumination. These results are all based in the chemisorption backside coating processes developed at the Steward Observatory CCD Laboratory.
• Wildi, F. P., Shelton, J. C., Schaller, S., Rhoadarmer, T. A., Rademacher, M. J., Ouellette, D. B., Mcguire, P. C., Lloyd-hart, M., Lesser, M. P., Kenworthy, M. A., Hughes, J. M., Fitz-patrick, B. C., Capara, J. G., Angeli, G. Z., & Angel, J. R. (1999). Construction and testing of the wavefront sensor camera for the new MMT adaptive optics system. In SPIE Proceedings, 3762, 269-282.
  More info

  This paper describes the construction and testing of the Shack-Hartmann wavefront sensor camera for the new MMT adaptive optics system. Construction and use of the sensor is greatly simplified by having the 12 X 12 lenslet array permanently glued to the detector array, obviating the need for any further realignment. The detector is a frame transfer CCD made by EEV with 80 by 80 pixels, each 24 microns square, and 4 output amplifiers operated simultaneously. 3 by 3 pixel binning is used to create in effect an array of quad-cells, each centered on a spot formed by a lenslet. Centration of the lenslet images is measured to have an accuracy of 1 micrometers rms. The maximum frame rate in the binned mode is 625 Hz, when the rms noise is 4.5-5 electrons. In use at the telescope, the guide star entering the wavefront sensor passes through a 2.4 arcsec squares field stop matched to the quall-cell size, and each lenslet samples a 54 cm square segment of the atmospherically aberrated wavefront to form a guide star image at a plate scale of 60 micrometers /arcsec. Charge diffusion between adjacent detector pixels is small: the signal modulation in 0.7 arcsec seeing is reduced by only 10 percent compared to an ideal quad-cell with perfectly sharp boundaries.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
• Blouke, M. M., Burmester, W., Clampin, M., Ford, H. C., Golimowski, D. A., Hartig, G. F., Illingworth, G. D., Kimble, R. A., Krebs, C. A., Lesser, M. P., Purdue, G., Sirianni, M., Sullivan, P. C., & Walkowicz, L. M. (1998).

  CCD detectors for the Advanced Camera for Surveys

  . In SPIE.
• Lesser, M. P. (1994). Improving CCD quantum efficiency. In Instrumentation in Astronomy VIII, 2198, 782-791.
  More info

  The enhancement of the quantum efficiency of charge-coupled devices (CCDs) can be accomplished by several methods. The most dramatic increase comes from thinning the CCD for use in the back illuminated mode. Techniques to improve the QE of back illuminated CCDs include the deposition of backside thin film coatings to reduce reflection losses, surface charging to eliminate the backside potential well, and several aspects of device packaging. We have developed processes in these areas which have led to the post-manufacture optimization of devices for astronomical observations. WE describe our backside oxidation results and the interaction of the oxide with backside charging, the effect of ion absorption on backside charging, the development of one and two-layer antireflection coatings, and a new packaging method to improve near-infrared quantum efficiency.
• Sims, G. R., Meyer, H. J., Lo, S., Lesser, M. P., Doherty, P. E., & Damento, M. A. (1994). Thinned 4096x4096 CCD mosaic. In SPIE Proceedings, 2172, 175-179.
  More info

  A thinned-CCD mosaic was fabricated from four Loral 2048 X 2048 edge-buttable CCDs. Thinning was performed on the whole wafer with subsequent dicing and handling facilitated by bonding the thinned wafer to a glass plate. Packaging of the devices involved a `flip-chip' wire-bonding technique followed by chemical dissolution of the glass support. The fabrication process was designed to minimize the gaps between devices and retain a high degree of flatness in the finished CCDs.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
• Smith, A. M., Skillman, D. R., Seery, B. D., Niedner, M. B., Lesser, M. P., Krebs, C. A., Heap, S. R., Hannan, P. G., Clampin, M., Brown, R. A., & Bolton, J. F. (1994). Hubble Space Telescope Advanced Camera conceptual design. In Instrumentation in Astronomy VIII, 2198, 1298-1314.
  More info

  A design for an advanced camera (AC) third-generation Hubble Space Telescope scientific instrument is discussed. The AC is a three-channel spectrophotometric camera with wavelength sensitivity from 115-1000 nm. The AC, if selected, would be launched in 1999 for installation on HST. The axial bay design incorporates optical correction for the aberrated HST primary mirror and evolutionary advances in imaging capability.
• Winzenread, R., Tseng, H., Terhune, R. W., Nikzad, S., Lesser, M. P., Hoenk, M. E., Grunthaner, P. J., Grunthaner, F. J., & Fattahi, M. M. (1994). Delta-doped CCDs: high QE with long-term stability at UV and visible wavelengths. In Instrumentation in Astronomy VIII, 2198, 907-915.
  More info

  Delta-doped CCDs, developed at JPL's Microdevices Laboratory, have achieved stable 100% internal quantum efficiency in the visible and near UV regions of the spectrum. In this approach, an epitaxial silicon layer is grown on a fully-processed commercial CCD using molecular beam epitaxy. During the silicon growth on the CCD, 30% of a monolayer of boron atoms are deposited on the surface, followed by a 15 $angstrom silicon layer for surface passivation. The boron is nominally incorporated within a single atomic layer at the back surface of the device, resulting in the effective elimination of the backside potential well. The measured quantum efficiency is in good agreement with the theoretical limit imposed by reflection from the Si surface. Enhancement of the total quantum efficiency in the blue visible and near UV has been demonstrated by depositing antireflection coatings on the delta-doped CCD. Recent results on antireflection coatings and quantum efficiency measurements are discussed.
• Wong, W., Reed, R., Lesser, M. P., & Boroson, T. A. (1994). Development of a 8192x8192 CCD mosaic imager. In Instrumentation in Astronomy VIII, 2198, 877-885.
  More info

  The next generation of CCD imagers will undoubtedly be mosaics, in order to overcome (1) the low yield when fabricating large devices, (2) the limited number of readout channels that can be put easily on a single CCD, and (3) the physical limitation of the 4-inch silicon wafer. As a first step towards a 8192 x 8192 CCD mosaic, we have recently fabricated a 2 x 2 array of Loral 2048 x 2048 CCDs. The two-side buttable design of these chips (by John Geary of SAO) allows us to achieve gaps of about 0.6 mm (40 pixels). This prototype mini-mosaic imager, using unthinned, front-illuminated CCDs has been used at the KPNO 0.9 m and 4 m telescopes. As we are constructing a number of scientific-grade mosaics with thinned chips for use at KPNO and CTIO, we are beginning the design and fabrication work for an 8192 x 8192 imager. This will be a 2 x 4 array of Loral 4096 x 2048 CCDs with interchip spacing of less than 0.5 mm. Such a device will have a physical size of approximately 5 inches square and will cover an area of 38.6 (59.1) arcminutes on an edge at the 4 m (0.9 m) telescope with a pixel size of 0.28 (0.43) arcseconds per pixel. This paper discusses results obtained with the 4096 x 4096 minimosaic and design strategies/progress on the larger 8192 x 8192 imager. Specifically, we present designs of the Dewar and mechanical interface for the large mosaic, a physical mounting scheme which will achieve better than 5 micron RMS flatness, and a discussion of the electronics and controller (the CTIO transputer-based ARCON), which will allow us to read out the entire array in less than two minutes. Some strategies for dealing with the large amount of data (128 Megabytes per image) will be presented.
• Lesser, M. P. (1993). Backside Coatings for Back illuminated CCDs. In SPIE Proceedings, 1900, 219-227.
  More info

  The optimization of back illuminated CCDs for low-light-level applications requires many process steps. One such step is the deposition of thin films on the freshly thinned backside surface. These films may consist of many layers depending on both the desired properties of the detector and on the backside charging mechanism. We describe our backside coating process which has been optimized for astronomical applications. After thinning, we first grow a thin silicon oxide film in a steam environment. Following oxidation we deposit an antireflection coating optimized for a particular wavelength. We may also deposit a thin film of platinum between these layers that acts to charge the backside. Using these thin film coatings we have been able to produce CCDs which reach silicon's theoretical maximum quantum efficiency over the 300 - 1000 nm wavelength region.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
• Ulrickson, L., Ouellette, D. B., Lesser, M. P., & Bauer, A. (1992). Bump-bonded back-illuminated CCDs. In SPIE Proceedings, 1656, 508-516.
  More info

  We have developed a thinning and packaging process which allows the conversion of front-illuminated charge-coupled devices (CCDs) into back illuminated sensors. This process does not depend on any special processing by the manufacturer and can therefore be used with any type of CCD. The process consists of several major steps which include: 1) making a silicon substrate with conductive traces and indium bumps which mate to the CCD wire bonding pads 2) placing indium bumps on the CCD wire bonding pads 3) bump bonding the substrate and CCD together 4) thinning 5)packaging 6) oxidizing the backside surface 7) applying antireflection coatings and 8) backside charging. Using this process with Loral 1200x800 and 3072x1024 CCDs we have produced devices with quantum efficiency in excess of 80 in the near-UV and visible wavelength regions. The surface flatness of these devices has been measured interferometrically to deviate from a plane by less than 1 um rms for the 1200x800 pixel sensors. 2.
• Wei, M., Schaeffer, A. R., Robinson, L. B., Lesser, M. P., Brown, W. E., & Bertling, P. P. (1992). Indium-tin-oxide biased-gate technology. In SPIE Proceedings, 1656, 517-525.
  More info

  Ongoing experiments using thin electrically conducting transparent layers of Indium Tin Oxide to control the surface potential of thinned CCDs are described. The results are very encouraging with good uniform ultraviolet sensitivity being obtained from CCDs of different types and thinned by different processes. The enhanced response is stable in air and in vacuum for periods longer than a year. 2.
• Lesser, M. P. (1991). Array detectors in astronomy. In SPIE Proceedings, 1439, 144-151.
  More info

  Charge-coupled devices (CCDs) have become extremely important detectors for the entire astronomical community. We discuss their properties in relation to astronomical imaging and spectroscopy. We also consider some of the improvements we hope to see to further their use in astronomy and other scientific fields. These include larger area detectors and mosaics of detectors with flat and stable packaging, antireflection coatings on back illuminated devices, and extremely low read noise for spectroscopic applications. We discuss some of our research into these areas.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
• Lesser, M. P. (1989). CCD Chemical/Mechanical Thinning Results. In New Methods in Microscopy and Low Light Imaging, 1161, 96-103.
  More info

  Charge-coupled devices (CCDs) are becoming increasingly used as the primary detector for many astronomical imaging and spectroscopic instruments. The major limitations of front-illuminated CCDs in this field are their lack of blue and UV spectral response and relatively poor visible light response. Thinned, back-illuminated CCDs can achieve significantly higher quantum efficiency but typically have a warped imaging surface, non-uniform flat-field response, and often do not respond well to backside charging techniques to eliminate the backside potential well. We describe here a novel thinning/polishing technique which produces an optically fiat imaging surface independent of the epitaxial/substrate interface location. Chemical/mechanical polishing can be used to thin a CCD when the final device thickness is greater 20pm or possible a wafer to any thickness. We discuss the effect of silicon thickness and thinning technique on surface warpage. We also discuss the bump bonding mounting method which we are beginning to use to improve the yield of the thinning process, the ease of backside charging and antireflection coating, and the ability to produce mosaics of CCDs for large focal planes such as the new generation of ground-based telescopes.
• Lesser, M. P., Olszewski, E. W., Sims, G. R., Olszewski, E. W., Lesser, M. P., & Griffin, F. (1989). Optimizing Charge -Coupled Devices for Red and Near -Infrared Observations. In SPIE Proceedings, 1071, 58-65.
  More info

  Methods to improve the red and near-IR quantum efficiency (QE) of CCDs are discussed. The effects of thinning, antireflection (AR) coating, and mounting CCDs for use in astronomical observations at wavelengths greater than 700 nm are presented. Thinning CCDs to inside their epitaxy and backside illuminating them increases their QE over thick devices even in the far red, due to the absence of frontside absorption and reflection losses. AR coatings decrease the backside reflection loss and greatly reduce the amplitudes of interference fringes. Mounting CCDs on a substrate eliminates surface warpage which improves the user's ability to correct for instrumental and background signatures. Some of these optimization techniques are demonstrated using the Photometrics PM512 CCD made by Ford Aerospace.
• Sims, G. R., Lesser, M. P., & Griffin, F. (1989). Improvements In CCD Quantum Efficiency In The UV And Near-IR. In SPIE Proceedings, 1071, 31-42.
  More info

  Improvements in CCD sensitivity in the UV and near-IR by using backside illumination, external backside accumulation, and wavelength conversion phosphors is discussed. Quantum efficiencies of greater than 50% in much of the UV and visible are reported through the use of backside illumination and either UV flood or flash gate backside accumulation. Problems with the environmental stability of backside accumulated CCDs and attempts to control the stability through the use of a biased flash gate is discussed. Significant QE gains in the near-IR through backside illumination without backside accumulation are reported. The use of a high-efficiency wavelength conversion phosphor to increase the UV sensitivity of frontside illuminated CCDs is presented. Results are presented that demonstrate that the QE of a typical polyphase frontside illuminated CCD can be increased from virtually zero to 20% in the UV.
• Sims, G. R., Lesser, M. P., & Griffin, F. (1989). Silicon CCD Optimized For Near Infrared (NIR) Wavelengths. In New Methods in Microscopy and Low Light Imaging, 1161, 55-60.
  More info

  Improvements in silicon CCD sensitivity in the NIR by using thick, high resistivity epitaxy silicon, backside illumination, and antireflection (AR) coatings are discussed. Quantum efficiencies at 900 nm of up to 42% for frontside illuminated devices and 78% backside illuminated and AR coated devices are reported.
• Lesser, M. P., & Hill, J. M. (1986). Deployment Of The Mx Spectrometer. In SPIE Proceedings, 627, 303-320.
  More info

  The MX Spectrometer is a remotely controlled multiple object fiber optic spectrometer head. Mobile fiber probes provide the capacity to obtain simultaneous spectra of many objects. Our experience with the Medusa aperture plate fiber optic spectrograph led us to design and build the MX with automated fiber positioning in the telescope focal plane. 32 stepper motor driven probes in a fishermen-around-the-pond arrangement position 64 fibers in the 45 arcminute field of the Steward Observatory 2.3m telescope. An onboard Z-80 microprocessor interfaces to 64 intelligent stepper motor controllers. The intelligent controllers allow simultaneous motion of all the probes for rapid field alignment. All fibers can be moved from one target pattern to another in less than 90 seconds. Two arcsecond diameter fiber apertures can be moved in steps as small as 0.1 arcseconds (10 microns). Probe collisions are prevented by software which maps the footprint of each probe in the focal plane. A failsafe electronic hardware system stops all motion in the unlikely event that two probes touch or encounter a foreign object. A second Z-80 with floppy disk drives is stationed in the control room to interface with the observer. This support microprocessor provides mass storage for coordinate lists as well as serial communications with the instrument microprocessor. We describe here both construction and actual operation of the MX Spectrometer at the telescope. The ability to record spectra of 32 objects plus additional sky spectra will greatly enhance our ability to study clustered systems of stars or galaxies.
• Lesser, M. P., Leach, R. W., & Angel, J. R. (1986). Thinning And Mounting A Texas Instruments 3-Phase CCD. In SPIE Proceedings, 627, 517-523.
  More info

  By having the ability to thin CCDs with precise control of thickness and surface quality astronomers will be able to optimize chips for specific applications. Traditional chemical etching is used to reduce subsurface damage of the silicon crystal lattice. We demonstrate a means of mechanically thinning a TI 800x800 CCD with an abrasive slurry of aluminum oxide. Using the same techniques we can replace the abrasives with a chemical solution to eliminate subsurface damage. We also demonstrate a technique of mounting the CCD which retains the high quality surface generated during thinning. This requires the backside of the chip to be bonded to a glass window which closely matches silicon's thermal expansion properties. Thinned CCDs require backside treatment to enhance blue and UV quantum efficiency. Two methods are discussed which may be effective with this mounting system. Due to silicon's high index of refraction in the visible spectral region up to 50 percent of the radiation incident onto a CCD can be lost to reflection. We briefly discuss the improvements to be gained from AR coating the backside.

Others

• {Comparat}, J., {Richard}, J., {Kneib}, J., {Ilbert}, O., {Gonzalez-Perez}, V., {Tresse}, L., {Zoubian}, J., {Arnouts}, S., {Bacon}, R., {Brownstein}, J., {Baugh}, C., {Delubac}, T., {Ealet}, A., {Escoffier}, S., {Ge}, J., {Jullo}, E., {Lacey}, C., {Ross}, N., {Schlegel}, D., , {Schneider}, D., et al. (2015, jan). VizieR Online Data Catalog: [OII] luminosity function (Comparat+, 2015). VizieR Online Data Catalog.