Ewan S Douglas

Interests

Teaching

Instrumentation, planetary atmospheres.

Research

CubeSats, Exoplanets, Circumstellar Debris Disks.

Courses

Scholarly Contributions

Journals/Publications

• Douglas, E. S., Debes, J., Mennesson, B., Nemati, B., Ashcraft, J., Ren, B., Stapelfeldt, K. R., Savransky, D., Lewis, N. K., & Macintosh, B. (2022). Sensitivity of the Roman Coronagraph Instrument to Exozodiacal Dust. PASP, 134(1032), 024402.
• Maier, E. R., Zellem, R. T., Colavita, M. M., Mennesson, B., Nemati, B., Bailey, V. P., Cady, E. J., Weisberg, C., Ryan, D., Belikov, R., Debes, J., Girard, J., Ygouf, M., Douglas, E., & Macintosh, B. (2022). Flatfield Calibrations with Astrophysical Sources for the Nancy Grace Roman Space Telescope's Coronagraph Instrument. arXiv e-prints, arXiv:2202.04815.
• Zellem, R. T., Nemati, B., Bailey, V. P., Cady, E. J., Colavita, M. M., Gonzalez, G., Hildebrandt, S. R., Maier, E. R., Mennesson, B., Ygouf, M., Zimmerman, N., Belikov, R., Debes, J., De, R., Douglas, E. S., Girard, J., Groff, T., Kasdin, J., Lowrance, P. J., , Macintosh, B., et al. (2022). Nancy Grace Roman Space Telescope Coronagraph Instrument Observation Calibration Plan. arXiv e-prints, arXiv:2202.05923.
• Douglas, E. S., Allan, G., Morgan, R. E., Cahoy, K., & al., e. (2021). Small {Mirrors} for {Small Satellites}: {Design} of the {Deformable Mirror Demonstration Mission CubeSat} ({DeMi}) {Payload}. Frontiers in Astronomy and Space Sciences Astronomical Instrumentation, Special Issue - Nanosatellites for Astronomy and Space Exploration.
• Douglas, E. S., Allan, G., Morgan, R., Holden, B. G., Gubner, J., Haughwout, C., Vale, P. P., Xin, Y., Merk, J., & Cahoy, K. L. (2021). Small Mirrors for Small Satellites: Design of the Deformable Mirror Demonstration Mission CubeSat (DeMi) Payload. Frontiers in Astronomy and Space Sciences, 8, 126.
• Douglas, E. S., Tracy, K., & Manchester, Z. (2021). Fundamental limits on Nanosatellite and CubeSat Telescope Pointing: The Impact of Disturbances and Photon Noise. Frontiers in Astronomy and Space Sciences, 8, 125.
• Douglas, E. S., Tracy, k., & Manchester, Z. (2021). Fundamental limits on {Nanosatellite} and {CubeSat Telescope Pointing}: {The Impact} of {Disturbances} and {Photon Noise}. Frontiers in Astronomy and Space Sciences Astronomical Instrumentation, Special Issue - Nanosatellites for Astronomy and Space Exploration.
• Jha, A. K., Douglas, E. S., Li, M., Fucetola, C., & Omenetto, F. G. (2021). Demonstration of magnetic and light-controlled actuation of a photomagnetically actuated deformable mirror for wavefront control. Optical Engineering, 60, 124102.
• Morgan, R., Douglas, E., Allan, G., Vale, P. P., Gubner, J., Haughwout, C., Holden, B., Murphy, T., Merk, J., Egan, M., Furesz, G., Roascio, D., Xin, Y., & Cahoy, K. (2021). Optical calibration and first light for the deformable mirror demonstration mission CubeSat (DeMi). Journal of Astronomical Telescopes, Instruments, and Systems, 7, 024002.
• Allan, G., Allan, G., Kang, I., Kang, I., Douglas, E. S., Barbastathis, G., Barbastathis, G., & Cahoy, K. (2020). Deep residual learning for low-order wavefront sensing in high-contrast imaging systems. Opt. Express, OE, 28(18), 26267--26283.
• Gaudi, B. S., Seager, S., Mennesson, B., Kiessling, A., Warfield, K., Cahoy, K., Clarke, J. T., Domagal-Goldman, S., Feinberg, L., Guyon, O., Kasdin, J., Mawet, D., Plavchan, P., Robinson, T., Rogers, L., Scowen, P., Somerville, R., Stapelfeldt, K., Stark, C., , Stern, D., et al. (2020). The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report. arXiv e-prints, arXiv:2001.06683.
• Maier, E. R., Hinz, P., Defr\`ere, D., Grenz, P., Downey, E., Ertel, S., Morzinski, K., & Douglas, E. S. (2020). Implementing multiwavelength fringe tracking for the large binocular telescope interferometer's phase sensor, {PHASECam}. Journal of Astronomical Telescopes, Instruments, and Systems, 6(3), 035001.
• Maier, E. R., Hinz, P., Defr{\`ere}, D., Grenz, P., Downey, E., Ertel, S., Morzinski, K., & Douglas, E. S. (2020). Implementing multiwavelength fringe tracking for the Large Binocular Telescope Interferometer's phase sensor, PHASECam. Journal of Astronomical Telescopes, Instruments, and Systems, 6, 035001.
• Mennesson, B., Juanola-Parramon, R. .., Nemati, B., Ruane, G., Bailey, V., Bolcar, M., Martin, S., Zimmerman, N., Stark, C., Pueyo, L., Benford, D., Cady, E., Crill, B., Douglas, E., Gaudi, B., Kasdin, J., Kern, B., Krist, J., Kruk, J., , Luchik, T., et al. (2020). Paving the Way to Future Missions: the Roman Space Telescope Coronagraph Technology Demonstration. arXiv e-prints, arXiv:2008.05624.
• Debes, J., Choquet, E., Faramaz, V. C., Duchene, G., Hines, D., Stark, C., Ygouf, M., Girard, J., Moro-Martin, A., Arriaga, P., Chen, C., Currie, T., Dodson-Robinson, S., Douglas, E. S., Kalas, P., Lisse, C. M., Mawet, D., Mazoyer, J., Mennesson, B., , Millar-Blanchaer, M. A., et al. (2019). Cold Debris Disks as Strategic Targets for the 2020s. \baas, 51(3), 566.
• Douglas, E. S. (2019). Cold Debris Disks as Strategic Targets for the 2020s. arXiv e-prints.
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  Cold debris disks (T$
• Douglas, E. S. (2019). CubeSats for Astronomy and Astrophysics. arXiv e-prints.
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  CubeSats have the potential to expand astrophysical discovery space, complementing ground-based electromagnetic and gravitational-wave observatories. The CubeSat design specifications help streamline delivery of instrument payloads to space. CubeSat planners have more options for tailoring orbits to fit observational needs and may have more flexibility in rapidly rescheduling observations to respond to transients. With over 1000 CubeSats launched, there has been a corresponding increase in the availability and performance of commercial-off-the-shelf (COTS) components compatible with the CubeSat standards, from solar panels and power systems to reaction wheels for three axis stabilization and precision attitude control. Commercially available components can reduce cost CubeSat missions, allowing more resources to be directed toward scientific instrument payload development and technology demonstrations....
• Douglas, E. S. (2019). Laser Guide Star for Large Segmented-aperture Space Telescopes. I. Implications for Terrestrial Exoplanet Detection and Observatory Stability. The Astronomical Journal.
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  Precision wavefront control on future segmented-aperture space telescopes presents significant challenges, particularly in the context of high-contrast exoplanet direct imaging. We present a new wavefront control architecture that translates the ground-based artificial guide star concept to space with a laser source on board a second spacecraft, formation flying within the telescope’s field of view. We describe the motivating problem of mirror segment motion and develop wavefront sensing requirements as a function of guide star magnitude and segment motion power spectrum. Several sample cases with different values for transmitter power, pointing jitter, and wavelength are presented to illustrate the advantages and challenges of having a non-stellar-magnitude noise limited wavefront sensor for space telescopes. These notional designs allow increased control authority, potentially relaxing spacecraft stability requirements by two orders of magnitude and increasing terrestrial exoplanet discovery space by allowing high-contrast observations of stars of arbitrary brightness....
• Douglas, E. S. (2019). MEMS Deformable Mirrors for Space-Based High-Contrast Imaging. Micromachines.
• Douglas, E. S., Cahoy, K. L., Knapp, M., & Morgan, R. E. (2019). CubeSats for Astronomy and Astrophysics. arXiv e-prints, arXiv:1907.07634.
• Douglas, E., Males, J., Clark, J., Guyon, O., Lumbres, J., Marlow, W., & Cahoy, K. (2019). Laser Guide Star for Large Segmented-aperture Space Telescopes. I. Implications for Terrestrial Exoplanet Detection and Observatory Stability. \aj, 157(1), 36.
• Lopez, E., Airapetian, V., Christiansen, J., Fossati, L., France, K., Angerhausen, D., Ardila, D., Arney, G., Bourrier, V., Dong, C., Douglas, E., Dragomir, D., Ehrenreich, D., Fortney, J., Frank, A., Gennaro, M., Kreidberg, L., Lecavelier, A., Lee, Y., , Louden, T., et al. (2019). Understanding Exoplanet Atmospheres with UV Observations II: The Far UV and Atmospheric Escape. \baas, 51(3), 522.
• Morgan, R. E., Douglas, E. S., Allan, G. W., Bierden, P., Chakrabarti, S., Cook, T., Egan, M., Furesz, G., Gubner, J. N., Groff, T. D., Haughwout, C. A., Holden, B. G., Mendillo, C. B., Ouellet, M., Vale, P. P., Stein, A. J., Thibault, S., Wu, X., Xin, Y., & Cahoy, K. L. (2019). MEMS Deformable Mirrors}} for {Space}-{Based High}-{{Contrast Imaging. Micromachines, 10(6), 366.
• Douglas, E. S. (2018). DeMi Payload Progress Update and Adaptive Optics (AO) Control Comparisons ─ Meeting Space AO Requirements on a CubeSat.
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  The Deformable Mirror (DeMi) CubeSat mission utilizes an Adaptive Optics (AO) control loop to correct incoming wavefronts as a technology demonstration for space-based imaging missions, such as high contrast observations (Earthlike exoplanets) and steering light into core single mode fibers for amplification. While AO has been used extensively on ground based systems to correct for atmospheric aberrations, operating an AO system on-board a small satellite presents different challenges. The DeMi payload 140 actuator MEMS deformable mirror (DM) corrects the incoming wavefront in four different control modes: 1) internal observation with a Shack-Hartmann Wavefront Sensor (SHWFS), 2) internal observation with an image plane sensor, 3) external observation with a SHWFS, and 4) external observation with an image plane sensor. All modes have wavefront aberration from two main sources, time-invariant launch disturbances that have changed the optical path from the expected path when calibrated in the lab and very low temporal frequency thermal variations as DeMi orbits the Earth. The external observation modes has additional error from: the pointing precision error from the attitude control system and reaction wheel jitter. Updates on DeMi’s mechanical, thermal, electrical, and mission design are also presented. The analysis from the DeMi payload simulations and testing provides information on the design options when developing space-based AO systems.
• Douglas, E. S. (2018). MagAO-X: project status and first laboratory results. ArXiv e-prints.
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  MagAO-X is an entirely new "extreme" adaptive optics system for the Magellan Clay 6.5 m telescope, funded by the NSF MRI program starting in Sep 2016. The key science goal of MagAO-X is high-contrast imaging of accreting protoplanets at H$\alpha$. With 2040 actuators operating at up to 3630 Hz, MagAO-X will deliver high Strehls (>70%), high resolution (19 mas), and high contrast ($< 1\times10^{-4}$) at H$\alpha$ (656 nm). We present an overview of the MagAO-X system, review the system design, and discuss the current project status.
• Douglas, E. S. (2018). Modeling coronagraphic extreme wavefront control systems for high contrast imaging in ground and space telescope missions. ArXiv e-prints.
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  The challenges of high contrast imaging (HCI) for detecting exoplanets for both ground and space applications can be met with extreme adaptive optics (ExAO), a high-order adaptive optics system that performs wavefront sensing (WFS) and correction at high speed. We describe two ExAO optical system designs, one each for ground-based telescopes and space-based missions, and examine them using the angular spectrum Fresnel propagation module within the Physical Optics Propagation in Python (POPPY) package. We present an end-to-end (E2E) simulation of the MagAO-X instrument, an ExAO system capable of delivering 6$\times10^{-5}$ visible-light raw contrast for static, noncommon path aberrations without atmosphere. We present a laser guidestar (LGS) companion spacecraft testbed demonstration, which uses a remote beacon to increase the signal available for WFS and control of the primary aperture segments of a future large space telescope, providing on order of a factor of ten factor improvement for relaxing observatory stability requirements. The LGS E2E simulation provides an easily adjustable model to explore parameters, limits, and trade-offs on testbed design and characterization.
• Douglas, E. S. (2018). Review of high-contrast imaging systems for current and future ground- and space-based telescopes I. Coronagraph design methods and optical performance metrics. ArXiv e-prints.
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  The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. In this first installment of a series of three papers summarizing the outcomes of the OOC workshop, we present an overview of design methods and optical performance metrics developed for coronagraph instruments. The design and optimization of coronagraphs for future telescopes has progressed rapidly over the past several years in the context of space mission studies for Exo-C, WFIRST, HabEx, and LUVOIR as well as ground-based telescopes. Design tools have been developed at several institutions to optimize a variety of coronagraph mask types. We aim to give a broad overview of the approaches used, examples of their utility, and provide the optimization tools to the community. Though it is clear that the basic function of coronagraphs is to suppress starlight while maintaining light from off-axis sources, our community lacks a general set of standard performance metrics that apply to both detecting and characterizing exoplanets. The attendees of the OOC workshop agreed that it would benefit our community to clearly define quantities for comparing the performance of coronagraph designs and systems. Therefore, we also present a set of metrics that may be applied to theoretical designs, testbeds, and deployed instruments. We show how these quantities may be used to easily relate the basic properties of the optical instrument to the detection significance of the given point source in the presence of realistic noise.
• Douglas, E. S. (2018). The Deformable Mirror Demonstration Mission (DeMi) CubeSat: optomechanical design validation and laboratory calibration. ArXiv e-prints.
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  Coronagraphs on future space telescopes will require precise wavefront correction to detect Earth-like exoplanets near their host stars. High-actuator count microelectromechanical system (MEMS) deformable mirrors provide wavefront control with low size, weight, and power. The Deformable Mirror Demonstration Mission (DeMi) payload will demonstrate a 140 actuator MEMS deformable mirror (DM) with \SI{5.5}{\micro\meter} maximum stroke. We present the flight optomechanical design, lab tests of the flight wavefront sensor and wavefront reconstructor, and simulations of closed-loop control of wavefront aberrations. We also present the compact flight DM controller, capable of driving up to 192 actuator channels at 0-250V with 14-bit resolution. Two embedded Raspberry Pi 3 compute modules are used for task management and wavefront reconstruction. The spacecraft is a 6U CubeSat (30 cm x 20 cm x 10 cm) and launch is planned for 2019.
• Douglas, E. S. (2018). The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Interim Report. ArXiv e-prints.
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  For the first time in human history, technologies have matured sufficiently to enable a mission capable of discovering and characterizing habitable planets like Earth orbiting sunlike stars other than the Sun. At the same time, such a platform would enable unique science not possible from ground-based facilities. This science is broad and exciting, ranging from new investigations of our own solar system to a full range of astrophysics disciplines. The Habitable Exoplanet Observatory, or HabEx, is one of four studies currently being undertaken by NASA in preparation for the 2020 Astrophysics Decadal Survey. HabEx has been designed to be the Great Observatory of the 2030s, with community involvement through a competed and funded Guest Observer (GO) program. This interim report describes the HabEx baseline concept, which is a space-based 4-meter diameter telescope mission concept with ultraviolet (UV), optical, and near-infrared (near-IR) imaging and spectroscopy capabilities. More information on HabEx can be found at https://www.jpl.nasa.gov/habex...
• Douglas, E. S. (2018). WFIRST Coronagraph Technology Requirements: Status Update and Systems Engineering Approach. Proceedings Volume, 1070526 (2018).
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  The coronagraphic instrument (CGI) on the Wide-Field Infrared SurveyTelescope (WFIRST) will demonstrate technologies and methods for high-contrastdirect imaging and spectroscopy of exoplanet systems in reflected light,including polarimetry of circumstellar disks. The WFIRST management and CGIengineering and science investigation teams have developed requirements for theinstrument, motivated by the objectives and technology development needs ofpotential future flagship exoplanet characterization missions such as the NASAHabitable Exoplanet Imaging Mission (HabEx) and the Large UV/Optical/IRSurveyor (LUVOIR). The requirements have been refined to supportrecommendations from the WFIRST Independent External Technical/Management/CostReview (WIETR) that the WFIRST CGI be classified as a technology demonstrationinstrument instead of a science instrument. This paper provides a descriptionof how the CGI requirements flow from the top of the overall WFIRST missionstructure through the Level 2 requirements, where the focus here is oncapturing the detailed context and rationales for the CGI Level 2 requirements.The WFIRST requirements flow starts with the top Program Level RequirementsAppendix (PLRA), which contains both high-level mission objectives as well asthe CGI-specific baseline technical and data requirements (BTR and BDR,respectively)... We also present the process and collaborative tools used inthe L2 requirements development and management, including the collection andorganization of science inputs, an open-source approach to managing therequirements database, and automating documentation. The tools created for theCGI L2 requirements have the potential to improve the design and planning ofother projects, streamlining requirement management and maintenance. [AbstractAbbreviated][Journal_ref: Proceedings Volume 10705, Modeling, Systems Engineering, and Project Management for Astronomy VIII; 1070526 (2018): SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States]
• Douglas, E. S. (2018). WFIRST Coronagraph Technology Requirements: Status Update and Systems Engineering Approach. ArXiv e-prints.
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  The coronagraphic instrument (CGI) on the Wide-Field Infrared Survey Telescope (WFIRST) will demonstrate technologies and methods for high-contrast direct imaging and spectroscopy of exoplanet systems in reflected light, including polarimetry of circumstellar disks. The WFIRST management and CGI engineering and science investigation teams have developed requirements for the instrument, motivated by the objectives and technology development needs of potential future flagship exoplanet characterization missions such as the NASA Habitable Exoplanet Imaging Mission (HabEx) and the Large UV/Optical/IR Surveyor (LUVOIR). The requirements have been refined to support recommendations from the WFIRST Independent External Technical/Management/Cost Review (WIETR) that the WFIRST CGI be classified as a technology demonstration instrument instead of a science instrument. This paper provides a description of how the CGI requirements flow from the top of the overall WFIRST mission structure through the Level 2 requirements, where the focus here is on capturing the detailed context and rationales for the CGI Level 2 requirements. The WFIRST requirements flow starts with the top Program Level Requirements Appendix (PLRA), which contains both high-level mission objectives as well as the CGI-specific baseline technical and data requirements (BTR and BDR, respectively)... We also present the process and collaborative tools used in the L2 requirements development and management, including the collection and organization of science inputs, an open-source approach to managing the requirements database, and automating documentation. The tools created for the CGI L2 requirements have the potential to improve the design and planning of other projects, streamlining requirement management and maintenance. [Abstract Abbreviated]
• Douglas, E. S. (2018). Wavefront sensing in space: flight demonstration II of the PICTURE sounding rocket payload. Journal of Astronomical Telescopes, Instruments, and Systems.
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  A NASA sounding rocket for high-contrast imaging with a visible nulling coronagraph, the Planet Imaging Concept Testbed Using a Rocket Experiment (PICTURE) payload, has made two suborbital attempts to observe the warm dust disk inferred around Epsilon Eridani. The first flight in 2011 demonstrated a 5 mas fine pointing system in space. The reduced flight data from the second launch, on November 25, 2015, presented herein, demonstrate active sensing of wavefront phase in space. Despite several anomalies in flight, postfacto reduction phase stepping interferometer data provide insight into the wavefront sensing precision and the system stability for a portion of the pupil. These measurements show the actuation of a 32 × 32-actuator microelectromechanical system deformable mirror. The wavefront sensor reached a median precision of 1.4 nm per pixel, with 95% of samples between 0.8 and 12.0 nm per pixel. The median system stability, including telescope and coronagraph wavefront errors other than tip, tilt, and piston, was 3.6 nm per pixel, with 95% of samples between 1.2 and 23.7 nm per pixel.
• Douglas, E. S., Mendillo, C. B., Cook, T. A., Cahoy, K. L., & Chakrabarti, S. (2018). Wavefront sensing in space: flight demonstration II of the PICTURE sounding rocket payload. Journal of Astronomical Telescopes, Instruments, and Systems, 4, 019003.
• Gaudi, B. S., Seager, S., Mennesson, B., Kiessling, A., Warfield, K., Kuan, G., Cahoy, K., Clarke, J. T., Domagal-Goldman, S., Feinberg, L., Guyon, O., Kasdin, J., Mawet, D., Robinson, T., Rogers, L., Scowen, P., Somerville, R., Stapelfeldt, K., Stark, C., , Stern, D., et al. (2018). The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Interim Report. arXiv e-prints, arXiv:1809.09674.
• Douglas, E. S. (2017). How CubeSats contribute to Science and Technology in Astronomy and Astrophysics.
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  CubeSats are nanosatellites, spacecraft typically the size of a shoebox or backpack. CubeSats are made up of one or more 10 cm x 10 cm x 10 cm units weighing 1.33 kg (each cube is called a “U”). CubeSats benefit from relatively easy and inexpensive access to space because they are designed to slide into fully enclosed spring-loaded deployer pods before being attached as an auxiliary payload to a larger vehicle, without adding risk to the vehicle or its primary payload(s). Even though CubeSats have inherent resource and aperture limitations due to their small size, over the past fifteen years, researchers and engineers have miniaturized components and subsystems, greatly increasing the capabilities of CubeSats. We discuss how state of the art CubeSats can address both science objectives and technology objectives in Astronomy and Astrophysics. CubeSats can contribute toward science objectives such as cosmic dawn, galactic evolution, stellar evolution, extrasolar planets and interstellar exploration.CubeSats can contribute to understanding how key technologies for larger missions, like detectors, microelectromechanical systems, and integrated optical elements, can not only survive launch and operational environments (which can often be simulated on the ground), but also meet performance specifications over long periods of time in environments that are harder to simulate properly, such as ionizing radiation, the plasma environment, spacecraft charging, and microgravity. CubeSats can also contribute to both science and technology advancements as multi-element space-based platforms that coordinate distributed measurements and use formation flying and large separation baselines to counter their restricted individual apertures.
• Douglas, E. S. (2017). Imaging the predicted asteroid belt analogue around Epsilon Eridani.
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  We propose to take advantage of the STIS coronagraphic mode and advances in speckle subtraction techniques to probe for scattered light from Epsilon Eridani's predicted asteroid belt analog. This proposal tests for the presence of visible scattered light from a warm dust ring at 1 arcsecond with a 5e-5/as^2 contrast, predicted from observations of the 24 micron excess. Dust morphology and scattered light brightness (exozodi) present a significant challenge to future exoplanet imaging missions, and Epsilon Eridani is an excellent sunlike candidate for future exoplanet direct imaging missions due its easily accessible habitable zone.Either a detection of scattered light from this circumstellar dust population or a non-detection will place valuable constraints on the dust composition, morphology, and transport mechanisms at work in the system and inform future direct imaging efforts of this nearby star system.
• Douglas, E. S. (2017). Simulating the WFIRST coronagraph Integral Field Spectrograph.
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  A primary goal of direct imaging techniques is to spectrally characterize the atmospheres of planets around other stars at extremely high contrast levels. To achieve this goal, coronagraphic instruments have favored integral field spectrographs (IFS) as the science cameras to disperse the entire search area at once and obtain spectra at each location, since the planet position is not known a priori. These spectrographs are useful against confusion from speckles and background objects, and can also help in the speckle subtraction and wavefront control stages of the coronagraphic observation. We present a software package, the Coronagraph and Rapid Imaging Spectrograph in Python (crispy) to simulate the IFS of the WFIRST Coronagraph Instrument (CGI). The software propagates input science cubes using spatially and spectrally resolved coronagraphic focal plane cubes, transforms them into IFS detector maps and ultimately reconstructs the spatio-spectral input scene as a 3D datacube. Simulated IFS cubes can be used to test data extraction techniques, refine sensitivity analyses and carry out design trade studies of the flight CGI-IFS instrument. crispy is a publicly available Python package and can be adapted to other IFS designs.
• Douglas, E. S. (2017). The DeMi CubeSat: Wavefront Control with a MEMS Deformable Mirror in Space.
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  High-contrast imaging instruments on future space telescopes will require precise wavefront correction to detect small exoplanets near their host stars. High-actuator count microelectromechanical system (MEMS) deformable mirrors provide a compact form of wavefront control. The 6U DeMi CubeSat will demonstrate wavefront control with a MEMS deformable mirror over a yearlong mission. The payload includes both an internal laser source and a small telescope, with both focal plane and pupil plane sensing, for deformable mirror characterization. We detail the DeMi payload design, and describe future astrophysics enabled by high-actuator count deformable mirrors and small satellites.
• Chakrabarti, S., Mendillo, C. B., Cook, T. A., Martel, J. F., Finn, S. C., Howe, G. A., Hewawasam, K., & Douglas, E. S. (2016). Planet Imaging Coronagraphic Technology Using a Reconfigurable Experimental Base (PICTURE-B): The Second in the Series of Suborbital Exoplanet Experiments. Journal of Astronomical Instrumentation, 5(1), 1640004-595.
• Douglas, E. S. (2016). Advancing spaceborne tools for the characterization of planetary ionospheres and circumstellar environments.
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  This work explores remote sensing of planetary atmospheres and their circumstellar surroundings. The terrestrial ionosphere is a highly variable space plasma embedded in the thermosphere. Generated by solar radiation and predominantly composed of oxygen ions at high altitudes, the ionosphere is dynamically and chemically coupled to the neutral atmosphere. Variations in ionospheric plasma density impact radio astronomy and communications. Inverting observations of 83.4 nm photons resonantly scattered by singly ionized oxygen holds promise for remotely sensing the ionospheric plasma density. This hypothesis was tested by comparing 83.4 nm limb profiles recorded by the Remote Atmospheric and Ionospheric Detection System aboard the International Space Station to a forward model driven by coincident plasma densities measured independently via ground-based incoherent scatter radar. A comparison study of two separate radar overflights with different limb profile morphologies found agreement between the forward model and measured limb profiles. A new implementation of Chapman parameter retrieval via Markov chain Monte Carlo techniques quantifies the precision of the plasma densities inferred from 83.4 nm emission profiles. This first study demonstrates the utility of 83.4 nm emission for ionospheric remote sensing. Future visible and ultraviolet spectroscopy will characterize the composition of exoplanet atmospheres; therefore, the second study advances technologies for the direct imaging and spectroscopy of exoplanets. Such spectroscopy requires the development of new technologies to separate relatively dim exoplanet light from parent star light. High-contrast observations at short wavelengths require spaceborne telescopes to circumvent atmospheric aberrations. The Planet Imaging Concept Testbed Using a Rocket Experiment (PICTURE) team designed a suborbital sounding rocket payload to demonstrate visible light high-contrast imaging with a visible nulling coronagraph. Laboratory operations of the PICTURE coronagraph achieved the high-contrast imaging sensitivity necessary to test for the predicted warm circumstellar belt around Epsilon Eridani. Interferometric wavefront measurements of calibration target Beta Orionis recorded during the second test flight in November 2015 demonstrate the first active wavefront sensing with a piezoelectric mirror stage and activation of a micromachine deformable mirror in space. These two studies advance our "close-to-home'' knowledge of atmospheres and move exoplanetary studies closer to detailed measurements of atmospheres outside our solar system.
• Douglas, E. S. (2016). Inverting OII 83.4 nm dayglow profiles using Markov chain radiative transfer.
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  Emission profiles of the resonantly scattered OII 83.4 nm triplet can in principle be used to estimate O+ density profiles in the F2 region of the ionosphere. Given the emission source profile, solution of this inverse problem is possible but requires significant computation. The traditional Feautrier solution to the radiative transfer problem requires many iterations to converge, making it time consuming to compute. A Markov chain approach to the problem produces similar results by directly constructing a matrix that maps the source emission rate to an effective emission rate which includes scattering to all orders. The Markov chain approach presented here yields faster results and therefore can be used to perform the O+ density retrieval with higher resolution than would otherwise be possible.
• Douglas, E. S. (2016). Planet Imaging Coronagraphic Technology Using a Reconfigurable Experimental Base (PICTURE-B): The Second in the Series of Suborbital Exoplanet Experiments.
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  The PICTURE-B sounding rocket mission is designed to directly image the exozodiacal light and debris disk around the Sun-like star Epsilon Eridani. The payload used a 0.5m diameter silicon carbide primary mirror and a visible nulling coronagraph which, in conjunction with a fine pointing system capable of 5milliarcsecond stability, was designed to image the circumstellar environment around a nearby star in visible light at small angles from the star and at high contrast. Besides contributing an important science result, PICTURE-B matures essential technology for the detection and characterization of visible light from exoplanetary environments for future larger missions currently being imagined. The experiment was launched from the White Sands Missile Range in New Mexico on 2015 November 24 and demonstrated the first space operation of a nulling coronagraph and a deformable mirror. Unfortunately, the experiment did not achieve null, hence did not return science results.
• Douglas, E. S. (2016). Radiometric calibration of a dual-wavelength, full-waveform terrestrial lidar. Sensors (Switzerland).
• Douglas, E. S. (2016). Spectroscopic Classification of AT2016cvv as a normal Type Ia Supernova.
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  We report spectroscopic classification of AT2016cvv (also known as PTSS-16ijc), discovered 2016 June 16.709 UT by the PMO-Tsinghua Supernova Survey (PTSS) in CGCG 280-024 (z=0.044571; Falco et al. 1999, PASP 111, 438, via NED), through inspection of an optical spectrum (range 370-690 nm, resolution 0.8 nm) obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak on 2016 June 19.347 UT. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, ApJ, 666, 1024) and GELATO (Harutyunyan et al. 2008, A & A, 488, 383) finds convincing spectral matches with a number of normal Type-Ia supernovae a few days before maximum light.
• Douglas, E. S. (2016). Spectroscopic Classification of AT2016cvw as a normal Type Ia Supernova.
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  We report spectroscopic classification of AT2016cvw (also known as PTSS-16ipw), discovered 2016 June 18.813 UT by the PMO-Tsinghua Supernova Survey (PTSS) in MCG +02-58-008 (z=0.038877; Huchra et al. 2012, ApJS, 199, 26, via NED), through inspection of an optical spectrum (range 370-690 nm, resolution 0.8 nm) obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak on 2016 June 20.423 UT. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, ApJ, 666, 1024) and GELATO (Harutyunyan et al. 2008, A & A, 488, 383) finds convincing spectral matches with a number of normal Type-Ia supernovae roughly 3 days before maximum light.
• Douglas, E. S. (2016). Wavefront sensing in space from the PICTURE-B sounding rocket.
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  A NASA sounding rocket for high contrast imaging with a visible nulling coronagraph, the Planet Imaging Coronagraphic Technology Using a Reconfigurable Experimental Base (PICTURE-B) payload has made two suborbital attempts to observe the warm dust disk inferred around Epsilon Eridani. We present results from the November 2015 launch demonstrating active wavefront sensing in space with a piezoelectric mirror stage and a micromachine deformable mirror along with precision pointing and lightweight optics in space.
• Geddes, G., Douglas, E., Finn, S. C., Cook, T., & Chakrabarti, S. (2016). Inverting OII 83.4 nm dayglow profiles using Markov chain radiative transfer. Journal of Geophysical Research (Space Physics), 121(11), 11,249-11,260.
• Leonard, D., Sheehan, P., McCarthy, D., Follette, K., Moustakas, J., Alaniz, M., Beaumont, C., Batterman, T., Black, E., Bowers, T., Cryder, M., Davis, C., Dawsey, R., Douglas, E., Gordon, S., Gramze, S., Greiner, M., Hart, K., Holt, A., , Hu, J., et al. (2016). Spectroscopic Classification of AT2016cvv as a normal Type Ia Supernova. The Astronomer's Telegram, 9171, 1.
• Leonard, D., Sheehan, P., McCarthy, D., Follette, K., Moustakas, J., Alaniz, M., Beaumont, C., Batterman, T., Black, E., Bowers, T., Cryder, M., Davis, C., Dawsey, R., Douglas, E., Gordon, S., Gramze, S., Greiner, M., Hart, K., Holt, A., , Hu, J., et al. (2016). Spectroscopic Classification of AT2016cvw as a normal Type Ia Supernova. The Astronomer's Telegram, 9173, 1.
• Li, Z., Jupp, D., Strahler, A., Schaaf, C., Howe, G., Hewawasam, K., Douglas, E., Chakrabarti, S., Cook, T., Paynter, I., Saenz, E., & Schaefer, M. (2016). Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar. Sensors, 16(3), 313.
• Cook, T., Cahoy, K., Chakrabarti, S., Douglas, E., Finn, S. C., Kuchner, M., Lewis, N., Marinan, A., Martel, J., Mawet, D., Mazin, B., Meeker, S. R., Mendillo, C., Serabyn, G., Stuchlik, D., & Swain, M. (2015). Planetary Imaging Concept Testbed Using a Recoverable Experiment-Coronagraph (PICTURE C). Journal of Astronomical Telescopes, Instruments, and Systems, 1, 044001.
• Douglas, E. S. (2015). ASASSN-15lo is a Post-Maximum Normal Type Ia Supernova.
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  We report spectroscopic classification of ASASSN-15lo (ATel #7673) through inspection of a low-dispersion optical spectrum (range 370-680 nm), obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak on 2015 June 20 UT.
• Douglas, E. S. (2015). ASASSN-15lu is a Type Ia Supernova.
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  We report spectroscopic classification of ASASSN-15lu (ATel #7698) in SDSS J132112.88+401556.7 (z=0.035037, via NED) through inspection of an optical spectrum (range 370-680 nm, resolution 0.8 nm), obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak on 2015 June 24.2 UT.
• Douglas, E. S. (2015). Capabilities and performance of dual-wavelength Echidna^® lidar.
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  We describe the capabilities and performance of a terrestrial laser scanning instrument built for the purpose of recording and retrieving the three-dimensional structure of forest vegetation. The dual-wavelength Echidna® lidar characterizes the forest structure at an angular resolution as fine as 1 mrad while distinguishing between leaves and trunks by exploiting their differential reflectances at two wavelengths: 1 and 1.5 μm. The instrument records the full waveforms of return signals from 5 ns laser pulses at half-nanosecond time resolution; obtains ±117 deg zenith and 360 deg azimuth coverage out to a radius of more than 70 m provides single-target range resolution of 4.8 and 2.3 cm for the 1 and 1.5 μm channels, respectively (1σ) and separates adjacent pulse returns in the same waveform at a distance of 52.0 and 63.8 cm apart for the 1 and 1.5 μm channels, respectively. The angular resolution is in part controlled by user-selectable divergence optics and is shown to be 〈2 mrad for the instrument's standard resolution mode, while the signal-to-noise ratio is 10 at 70 m range for targets with leaf-like reflectance for both channels. The portability and target differentiation make the instrument an ideal ground-based lidar suited for vegetation sensing.
• Douglas, E. S. (2015). End-to-end simulation of high-contrast imaging systems: methods and results for the PICTURE mission family.
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  We describe a set of numerical approaches to modeling the performance of space flight high-contrast imaging payloads. Mission design for high-contrast imaging requires numerical wavefront error propagation to ensure accurate component specifications. For constructed instruments, wavelength and angle-dependent throughput and contrast models allow detailed simulations of science observations, allowing mission planners to select the most productive science targets. The PICTURE family of missions seek to quantify the optical brightness of scattered light from extrasolar debris disks via several high-contrast imaging techniques: sounding rocket (the Planet Imaging Concept Testbed Using a Rocket Experiment) and balloon flights of a visible nulling coronagraph, as well as a balloon flight of a vector vortex coronagraph (the Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph, PICTURE-C). The rocket mission employs an on-axis 0.5m Gregorian telescope, while the balloon flights will share an unobstructed off-axis 0.6m Gregorian. This work details the flexible approach to polychromatic, end-to-end physical optics simulations used for both the balloon vector vortex coronagraph and rocket visible nulling coronagraph missions. We show the preliminary PICTURE-C telescope and vector vortex coronagraph design will achieve 10-8 contrast without post-processing as limited by realistic optics, but not considering polarization or low-order errors. Simulated science observations of the predicted warm ring around Epsilon Eridani illustrate the performance of both missions.
• Douglas, E. S. (2015). Error Analysis of O+ Density Retrieved from Combined 83.4 nm and 61.7 nm EUV dayglow.
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  One of the brightest features of Earth's EUV dayglow is the OII 83.4 nm line, which is excited by solar EUV/XUV photons and photoelectron flux. The emission is optically thick and resonantly scatters off of O+ ions in the F2 region of the ionosphere. Given neutral densities and the emission source, a limb scan of OII 83.4 nm intensity can be inverted to retrieve the underlying O+ density. The optically thin OII 61.7 nm emission is excited by the same mechanism and can serve as a proxy for the 83.4 nm source, but the two are not perfectly correlated due to their different absorption cross sections. We apply Bayesian analysis and a statistical model of the multiple scattering to investigate how uncertainties in 61.7 nm measurements, neutral densities and cross sections, and scattering cross sections affect uncertainty in retrieved O+ densities for Chapman ionosphere.
• Douglas, E. S. (2015). Optical Spectroscopy of PSN J15044078+1237436.
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  We report on optical spectroscopic observations of PSN J15044078+1237436 in NGC 5837 (z = 0.028723; Fisher et al. 1995, ApJ Suppl 100, 69, via NED) taken on 2015 June 20.3 and 2015 June 21.3 UT with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak.
• Douglas, E. S. (2015). PSN J11473508+5558147 is a Type Ib Supernova Near Maximum Light.
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  We report spectroscopic classification of PSN J11473508+5558147 through inspection of a low-dispersion optical spectrum (range 370-680 nm), obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak on 2015 June 21 UT.
• Douglas, E. S. (2015). Planetary Imaging Concept Testbed Using a Recoverable Experiment-Coronagraph (PICTURE C).
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  An exoplanet mission based on a high-altitude balloon is a next logical step in humanity's quest to explore Earthlike planets in Earthlike orbits orbiting Sunlike stars. The mission described here is capable of spectrally imaging debris disks and exozodiacal light around a number of stars spanning a range of infrared excesses, stellar types, and ages. The mission is designed to characterize the background near those stars, to study the disks themselves, and to look for planets in those systems. The background light scattered and emitted from the disk is a key uncertainty in the mission design of any exoplanet direct imaging mission, thus, its characterization is critically important for future imaging of exoplanets.
• Douglas, E. S. (2015). Supernova 2015Q in NGC 3888 = Psn J11473508+5558147.
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  P. Wiggins, Tooele, UT, USA, reports his discovery of an apparent supernova (mag about 16.0) on an unfiltered CCD frame taken June 17.299 UT using a 0.35-m f/5.5 reflector near Erda, Utah. The new object is located at R.A. = 11h47m35s.08, Decl. = +55d58'14".7 (equinox 2000.0), just north of the center of NGC 3888. Wiggins notes that nothing was visible at this position on an image taken on June 14 (no limiting magnitude provided). The discovery image was posted at URL http://www.slas.us/gallery2/main.php?g2_itemId=6246. The variable was designated PSN J11473508+5558147 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2015Q based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2015Q: June 18.898, 16.3 (G. Masi; remotely using a 43-cm telescope at Ceccano, Italy; position end figures 35s.08, 14".7); 19.235, 17.4 (J. Brimacombe, Cairns, Australia; position end figures 35s.22, 15".2; image posted at URL https://www.flickr.com/photos/43846774@N02/18981738816/); 19.905, 16.3 (R. Belligoli, F. Castellani, and C. Marangoni, Verona, Italy; Ritchey-Chretien 0.4-m reflector; position end figures 35s.06, 15".3; offset 5".6 east, 12".9 north; image posted via URL http://tinyurl.com/nnj3nnf). D. C. Leonard, San Diego State University; P. Sheehan and D. McCarthy, University of Arizona; K. Follette, Stanford University; J. Moustakas, Siena College; and D. Cantillo, A. Cazares-Kelly, S. Cazares-Kelly, Y. Cendes, N. Damm, A. Donati, E. Douglas, L. Ferrell, H. Fosbiner-Elkins, C. Fox, M. Greenberg, K. Hart, H. Hensley, A. Holt, E. Hooper, C. Juran, J. Keane, K. Key, L. Korus, T. Lee, K. Leidig, E. Merchak, K. Nessmann, S. Pendyala, S. Pirkl, J. Reeder, A. Roos, S. Rounseville, E. Ruddy, A. Schlingman, W. Schlingman, W. M. Schlingman, E. Schwartzman, V. Shanmugam, E. Silver, A. Stein, N. Stock, B. Svoboda, B. Thomas, N. Thomas, K. Thompson-Taylor, and H. Walton, 2015 Advanced Teen Astronomy Camp, report on optical spectroscopy of PSN J11473508+5558147 = SN 2015Q through inspection of a low-dispersion optical spectrogram (range 370-680 nm; resolution 0.8 nm) obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak on June 21 UT. PSN J11473508+5558147 = SN 2015Q is a type-Ib supernova; cross- correlation with a library of supernova spectra using the comparison tool GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) finds good matches with near-maximum type-Ib supernovae at a redshift of 0.008, consistent with the NED redshift of the putative host galaxy, NGC 3888 (de Vaucouleurs et al. 1991, RC3 catalogue).
• Douglas, E. S. (2015). The low-order wavefront sensor for the PICTURE-C mission.
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  The PICTURE-C mission will fly a 60 cm off-axis unobscured telescope and two high-contrast coronagraphs in successive high-altitude balloon flights with the goal of directly imaging and spectrally characterizing visible scattered light from exozodiacal dust in the interior 1-10 AU of nearby exoplanetary systems. The first flight in 2017 will use a 10-4 visible nulling coronagraph (previously flown on the PICTURE sounding rocket) and the second flight in 2019 will use a 10-7 vector vortex coronagraph. A low-order wavefront corrector (LOWC) will be used in both flights to remove time-varying aberrations from the coronagraph wavefront. The LOWC actuator is a 76-channel high-stroke deformable mirror packaged on top of a tip-tilt stage. This paper will detail the selection of a complementary high-speed, low-order wavefront sensor (LOWFS) for the mission. The relative performance and feasibility of several LOWFS designs will be compared including the Shack-Hartmann, Lyot LOWFS, and the curvature sensor. To test the different sensors, a model of the time-varying wavefront is constructed using measured pointing data and inertial dynamics models to simulate optical alignment perturbations and surface deformation in the balloon environment.
• Douglas, E. S., Martel, J., Li, Z., Howe, G., Hewawasam, K., Marshall, R. A., Schaaf, C. L., Cook, T. A., Newnham, G. J., Strahler, A., & Chakrabarti, S. (2015). Finding Leaves in the Forest: The Dual-Wavelength Echidna Lidar. IEEE Geoscience and Remote Sensing Letters, 12(4), 776-780.
• Howe, G. A., Hewawasam, K., Douglas, E. S., Martel, J., Li, Z., Strahler, A., Schaaf, C., Cook, T. A., & Chakrabarti, S. (2015). Capabilities and performance of dual-wavelength Echidna$^{\textregistered}$ lidar. Journal of Applied Remote Sensing, 9, 095979.
• Leonard, D., Sheehan, P., McCarthy, D., Follette, K., Moustakas, J., Cantillo, D., Cazares-Kelly, A. .., Cazares-Kelly, S. .., Cendes, Y., Damm, N., Donati, A., Douglas, E., Ferrell, L., Fosbiner-Elkins, H. .., Fox, C., Greenberg, M., Hart, K., Hensley, H., Holt, A., , Hooper, E., et al. (2015). ASASSN-15lo is a Post-Maximum Normal Type Ia Supernova. The Astronomer's Telegram, 7675, 1.
• Leonard, D., Sheehan, P., McCarthy, D., Follette, K., Moustakas, J., Cantillo, D., Cazares-Kelly, A. .., Cazares-Kelly, S. .., Cendes, Y., Damm, N., Donati, A., Douglas, E., Ferrell, L., Fosbiner-Elkins, H. .., Fox, C., Greenberg, M., Hart, K., Hensley, H., Holt, A., , Hooper, E., et al. (2015). ASASSN-15lu is a Type Ia Supernova. The Astronomer's Telegram, 7707, 1.
• Leonard, D., Sheehan, P., McCarthy, D., Follette, K., Moustakas, J., Cantillo, D., Cazares-Kelly, A. .., Cazares-Kelly, S. .., Cendes, Y., Damm, N., Donati, A., Douglas, E., Ferrell, L., Fosbiner-Elkins, H. .., Fox, C., Greenberg, M., Hart, K., Hensley, H., Holt, A., , Hooper, E., et al. (2015). Optical Spectroscopy of PSN J15044078+1237436. The Astronomer's Telegram, 7690, 1.
• Leonard, D., Sheehan, P., McCarthy, D., Follette, K., Moustakas, J., Cantillo, D., Cazares-Kelly, A. .., Cazares-Kelly, S. .., Cendes, Y., Damm, N., Donati, A., Douglas, E., Ferrell, L., Fosbiner-Elkins, H. .., Fox, C., Greenberg, M., Hart, K., Hensley, H., Holt, A., , Hooper, E., et al. (2015). PSN J11473508+5558147 is a Type Ib Supernova Near Maximum Light. The Astronomer's Telegram, 7680, 1.
• Wiggins, P., Masi, G., Brimacombe, J., Belligoli, R., Castellani, F., Marangoni, C., Leonard, D., Sheehan, P., McCarthy, D., Follette, K., Moustakas, J., Cantillo, D., Cazares-Kelly, A. .., Cendes, Y., Damm, N., Donati, A., Douglas, E., Ferrell, L., Fosbiner-Elkins, H. .., , Fox, C., et al. (2015). Supernova 2015Q in NGC 3888 = Psn J11473508+5558147. Central Bureau Electronic Telegrams, 4128, 1.
• Douglas, E. S. (2014). Evaluation of Ionospheric Parameters Obtained by Inverting O II 83.4 nm Dayglow Profiles from RAIDS.
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  We test ionospheric parameters obtained by inverting O II 83.4 nm dayglow profiles against coincident ground-based measurements of electron density. Limb profiles from the Remote Atmospheric and Ionospheric Detection System (RAIDS) EUV Spectrograph on the International Space Station (ISS) are compared to a radiative transfer model which assumes a Chapman-α electron density profile fit to an independent ground-based measurement.
• Douglas, E. S. (2014). Finding leaves in the forest: The dual-wavelength Echidna lidar. IEEE Geoscience and Remote Sensing Letters.
• Douglas, E. S. (2014). Modeling of Expected PICTURE Observations of Exozodiacal Dust Around Epsilon Eridani.
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  The PICTURE (Planetary Imaging Concept Testbed Using a Rocket Experiment) sounding rocket will use a visible nulling coronagraph to characterize the exozodiacal dust disk of Epsilon Eridani (K2V, 3.22 pc) in reflected visible light to an inner radius of 1.5 AU (0.5") from the surface of the star. The first launch of PICTURE suffered a telemetry failure and the primary mirror was shattered upon landing. A new launch is scheduled and the PICTURE payload is currently undergoing refurbishment, including receiving a new SiC primary mirror. PICTURE visible light observations will constrain scattering properties of the Epsilon Eridani exozodiacal dust disk and measure the background brightness of the system which must be overcome for future exoplanet observations. Additionally, PICTURE will demonstrate operation of a MEMS deformable mirror and a visible nulling coronagraph in space. Improved modeling and post-flight measurement of instrument performance allow us to present refined exozodiacal dust sensitivities.
• Douglas, E. S. (2014). Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph.
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  We present the design and expected performance of PICTURE-C, a new suborbital mission designed to image debris disks around stars hosting exoplanets. We present the mission design, expected capabilities, and status. Potential targets, observing scenarios, and expected results are also discussed.
• Douglas, E. S. (2014). Recent Contrast Measurements Made Using the PICTURE Visible Nulling Coronagraph.
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  The PICTURE-B (Planetary Imaging Concept Testbed Using a Rocket Experiment - B) sounding rocket mission will use a visible nulling coronagraph to directly image the exozodiacal dust disk of Epsilon Eridani (K2V, 3.22 pc) in reflected visible light down to an inner radius of 1.5 AU (1.7 λ/D). This mission will demonstrate a number of key technologies for future space-based direct exoplanet imaging missions. These include: wavefront sensing and control using deformable mirrors in space, a lightweight SiC 0.5 meter primary mirror and a milliarcsecond-class fine pointing system. The mission is scheduled for launch in October, 2014. We present laboratory contrast measurements made using the PICTURE-B instrument and model predictions of exozodiacal dust detection limits based on these measurements.
• Douglas, E. S. (2014). Status of the PICTURE Sounding Rocket to Image the Epsilon Eridani Circumstellar Environment.
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  The PICTURE (Planetary Imaging Concept Testbed Using a Rocket Experiment) sounding rocket will use a visible nulling interferometer to characterize the exozodiacal dust disk of Epsilon Eridani (K2V, 3.22 pc) in reflected visible light to an inner radius of 1.5 AU (0.5”) from the star. Launch is scheduled for Fall 2014 and the PICTURE payload is currently undergoing re-integration. The first launch of PICTURE suffered a science telemetry failure and the primary mirror was shattered upon landing, the second launch will fly a new SiC primary mirror and onboard data storage. PICTURE visible light observations will constrain scattering properties of the Epsilon Eridani exozodiacal dust disk from 600nm to 750 nm, measuring the background brightness which must be overcome for future exoplanet observations. Additionally, PICTURE will demonstrate operation of a MEMS deformable mirror and a visible nulling coronagraph in space. We will present the latest measurements of integrated telescope and interferometer performance.
• Douglas, E. S. (2014). Structure Measurements of Leaf and Woody Components of Forests with Dual-Wavelength Lidar Scanning Data.
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  Forest structure plays a critical role in the exchange of energy, carbon and water between land and atmosphere and nutrient cycle. We can provide detailed forest structure measurements of leaf and woody components with the Dual Wavelength Echidna® Lidar (DWEL), which acquires full-waveform scans at both near-infrared (NIR, 1064 nm) and shortwave infrared (SWIR, 1548 nm) wavelengths from simultaneous laser pulses. We collected DWEL scans at a broadleaf forest stand and a conifer forest stand at Harvard Forest in June 2014. Power returned from leaves is much lower than from woody materials such as trunks and branches at the SWIR wavelength due to the liquid water absorption by leaves, whereas returned power at the NIR wavelength is similar from both leaves and woody materials. We threshold a normalized difference index (NDI), defined as the difference between returned power at the two wavelengths divided by their sum, to classify each return pulse as a leaf or trunk/branch hit. We obtain leaf area index (LAI), woody area index (WAI) and vertical profiles of leaf and woody components directly from classified lidar hits without empirical wood-to-total ratios as are commonly used in optical methods of LAI estimation. Tree heights, diameter at breast height (DBH), and stem count density are the other forest structure parameters estimated from our DWEL scans. The separation of leaf and woody components in tandem with fine-scale forest structure measurements will benefit studies on carbon allocation of forest ecosystems and improve our understanding of the effects of forest structure on ecosystem functions. This research is supported by NSF grant, MRI-0923389
• Douglas, E. S. (2014). Using the Rapid-Scanning, Ultra-Portable, Canopy Biomass Lidar (CBL) Alone and In Tandem with the Full-Waveform Dual-Wavelength Echidna^® Lidar (DWEL) to Establish Forest Structure and Biomass Estimates in a Variety of Ecosystems.
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  Terrestrial lidars are increasingly being deployed in a variety of ecosystems to calibrate and validate large scale airborne and spaceborne estimates of forest structure and biomass. While these lidars provide a wealth of high resolution information on canopy structure and understory vegetation, they tend to be expensive, slow scanning and somewhat ponderous to deploy. Therefore, frequent deployments and characterization of larger areas of a hectare or more can still be challenging. This suggests a role for low cost, ultra-portable, rapid scanning (but lower resolution) instruments -- particularly in scanning extreme environments and as a way to augment and extend strategically placed scans from the more highly capable lidars. The Canopy Biomass Lidar (CBL) is an inexpensive, highly portable, fast-scanning (33 seconds), time-of-flight, terrestrial laser scanning (TLS) instrument, built in collaboration with RIT, by U Mass Boston. The instrument uses a 905nm SICK time of flight laser with a 0.25o resolution and 30m range. The higher resolution, full-waveform Dual Wavelength Echidna® Lidar (DWEL), developed by Boston University, U Mass Lowell and U Mass Boston, builds on the Australian CSIRO single wavelength, full-waveform Echidna® Validation Instrument (EVI), but utilizes two simultaneous laser pulses at 1064 and 1548 nm to separate woody returns from those of foliage at a range of up to 100m range. The UMass Boston CBL has been deployed in rangelands (San Joaquin Experimental Range, CA), high altitude conifers (Sierra National Forest, CA), mixed forests (Harvard Forest LTER MA), tropical forests (La Selva and Sirena Biological Stations, Costa Rica), eucalypts (Karawatha, Brisbane TERN, Australia), and woodlands (Alice Holt Forest, UK), frequently along-side the DWEL, as well as in more challenging environments such as mangrove forests (Corcovado National Park, Costa Rica) and Massachusetts salt marshes and eroding bluffs (Plum Island LTER, and UMass Boston Nantucket Field Station). Multiple hemispherical point clouds can be combined to generate detailed reconstructions of ecosystem biomass and structure. By combining these scans and reconstructions, the strengths of the DWEL can be coupled with the speed and portability of the CBL to extrapolate comprehensive structure information to larger areas.
• Douglas, E. S. (2013). Canopy Biomass Lidar (CBL) Acquisitions at NEON and TERN Forest Sites.
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  Terrestrial Laser Scanning (TLS) offers the ability to capture complex forest structure through 3D reconstruction of multiple laser return point clouds. These reconstructions provide detailed information on understory, mid-story and canopy structure and allow quantification of important ecosystem factors such as biomass, vegetation productivity, forest health and response to disturbance. Used in conjunction with airborne lidar and satellite imaging, TLS is a powerful calibration/validation tool for improved regional scale ecological surveying and modeling. Repeated deployments facilitate the estimation of growth rates, nutrient fluxes, and other essential parameters in global scale climate and biogeochemic modeling. Routine TLS acquisitions at long-term research sites provide an opportunity to capture temporal variations due to natural and anthropogenic effects. While discrete return and full waveform TLS instruments (such as the Dual Wavelength Echidna Lidar (DWEL)) are increasingly being deployed, there is also a need for high speed, low-cost, highly portable TLS instruments to augment these more powerful, high resolution lidars. The Canopy Biomass Lidar (CBL) is a light, fast-scanning, time-of-flight, 905nm, TLS instrument, conceived by the Katholieke Universiteit Leuven (KUL) and refined by the Rochester Institute of Technology (RIT). Two CBLs, constructed by the University of Massachusetts Boston, were deployed alongside the full waveform DWEL (developed by Boston University, University of Massachusetts Lowell, University of Massachusetts Boston, and the Commonwealth Scientific and Industrial Research Organisation (CSIRO)) during the June 2013 NEON Airborne Observation Platform (AOP) campaign in the Sierra National Forest, CA. Three sites were characterized by both the CBLs and the DWEL in the Soaproot and Teakettle regions (where relocatable NEON towers will be situated). Up to 5 multiple scans were acquired by the DWEL, with an additional 8-12 scans obtained with the CBLs, to generate coincident 3D point clouds. Additional NEON sites in the Soaproot region were also scanned by the RIT CBL, while field teams collected forestry measures and LAI estimates. NEON full waveform airborne LiDAR and hyperspectral imagery were captured concurrently. In July 2013, the UMB CBL scanners were again deployed alongside the DWEL at three long term forest monitoring locations in Queensland, Australia as part of a TLS field activity, sponsored by the Terrestrial Laser Scanning International Interest Group (TLSiig), the Terrestrial Ecosystem Research Network (TERN) and CSIRO, Australia. The sites were located at Karawatha Forest Park, a TERN Supersite location and in the Brisbane Forest Park portion of D'Aguilar National Park. Again multiple scans were acquired over each 50x50m site (13 lower range CBL scans interposed at and between the DWEL scans) to generate multiple point clouds and detailed 3D reconstructions. These and further efforts this fall in the vicinity of the NEON tower site at Harvard Forest, MA, recognize the substantial value TLS offers to ongoing data collection at globally-recognized long-term field sites such as NEON and TERN. Highly-portable TLS such as the CBL allow efficient, frequent, expansive, and rapid response sampling to augment the more detailed information possible from instruments like the DWEL.
• Douglas, E. S. (2013). Coastal Applications of the Canopy Biomass Lidar (CBL).
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  Airborne discrete and full waveform lidars have increasingly been utilized to augment multispectral and hyperspectral imaging of coastal ecosystems. While these data provide important landscape assessments of the shore and nearshore environment, they often lack the frequency that is really needed to monitor complex vegetative systems such as salt marshes and mangroves and provide rapid evaluations in the aftermath of severe storms. One solution is to augment the sparse airborne and satellite acquisitions with terrestrial laser scanning (TLS) information. However, most institutions with fine resolution discrete or full waveform TLS instruments are unwilling to risk these expensive (and often heavy) lidar in marine or estuarine environments. The Canopy Biomass Lidar (CBL) is an inexpensive, highly portable, fast-scanning, time-of-flight, TLS instrument, originally conceived by the Katholieke Universiteit Leuven (KUL) and refined by the Rochester Institute of Technology (RIT). Two new CBLs, constructed by the University of Massachusetts Boston (UMB), have been successfully deployed in deciduous and conifer forests at Long Term Ecological Research (LTER) and National Ecological Observatory Network (NEON) sites in Massachusetts (Harvard Forest) and California (Sierra National Forest), and in eucalypt forests at long-term and Terrestrial Ecosystem Research Network (TERN) sites in Queensland, Australia. Both the UMB and RIT CBLs have also been deployed in savanna systems at the San Joaquin Rangeland (and NEON site) in California. The UMB CBLs are now being deployed in salt marsh systems in Massachusetts with plans underway to deploy them in mangrove forests later in the year. In particular, they are being used to characterize the water facing edge of saltmarsh at UMB's Nantucket Island field station and remnant salt marshes on the highly urbanized Neponset estuary draining into Boston Harbor. While CBL's 905nm nearIR wavelength is of little use in nearshore inundated systems (such as eel grass and kelp), it is excellent for characterizing 3D foliage structure via multiple scan point clouds. The system is light and the scanning is rapid enough (30seconds for a full hemispherical scan) to be deployed manually or in small watercraft. The portability also means that it can be used frequently to monitor vegetation dynamics throughout the growing season and assess marsh damage and erosion after severe storms. While airborne lidar and hyperspectral data and high resolution satellite imagery (and indeed even the more frequently available coarser resolution multispectral satellite imagery from the newly launched Landsat 8) will provide the most expansive views of such environments, tools such as the CBL can provide important ancillary information to augment the remote sensing data and provide rapid and fine scale shore level details to improve modeling and monitoring of these coastal vegetation ecosystems.
• Douglas, E. S. (2013). Field Deployments of DWEL, A Dual-Wavelength Echidna Lidar.
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  We describe the construction and operation of a terrestrial scanning lidar used for automated retrieval of forest structure. The Dual Wavelength Echidna Lidar (DWEL) distinguishes between leaf hits and those of trunks and branches by using simultaneous, co-axial laser pulses at 1548 nm, where leaf water content produces strong absorption, and at 1064 nm where leaves and trunks have similar reflectances. The DWEL instrument obtains three-dimensional locations and characteristics of scattering events by using an altitudinal scan mirror on an azimuthal rotating mount along with full waveform digitization. The instrument has seen two successful field deployments: to the Sierra National Forest, California in June of 2013 and to both the Karawatha Forest Park and Brisbane Forest Park near Brisbane, Australia in July/August 2013 as part of the Terrestrial Laser Scanner International Interest Group (TLSIIG) conference. Measurements of tree leaves, branches, and trunks were successfully made. Panels of known reflectance were used to calibrate and characterize the back scattered waveforms in the field. Preliminary maximum range measurements were shown to be over 75 meters for both wavelengths. To obtain accurate waveform data, the two lasers are triggered simultaneously and each has a full-width-half-max length of less than 10 meters. The light is then collimated and expanded to a diameter of 6 mm before diverging in user-selectable optics with divergences of either 1.25- or 2.5-mrad enabling scan resolutions of 1- and 2-mrad. The durations of complete scans are approximately 164 and 41 minutes, respectively. Mirrors and dichroic filters co-align the two NIR wavelength laser beams along with a continuous-wave green marker laser. The outgoing beams are directed by a rotating 10 cm scan mirror with effective field of view of ×110 degrees attitudinally while the instrument itself rotates for an effective azimuthal field of view of 360 degrees. Optical encoders in both planes provide at least 15-bit precision per rotation. The back-scattered return signal arriving at the scan mirror enters a 10-cm Newtonian-Nasmyth telescope and is split using a dichroic beamsplitter and narrow band pass filters. InGaAs photodiodes measure the return signals at each wavelength which are sampled at 2 gigasamples per second with 10-bit precision. Waveform and housekeeping data are first collected by an on-board compactPCI single-board computer before being transmitted live via Ethernet to a separate field PC. The required 115 W of power is supplied by high-density lithium ion batteries which together with the instrument bring the total weight to around 21 kg. The instrument has been designed to be eye-safe. In this presentation we will describe the features of the instrument along with data collected from the field campaigns. This work was made possible by the US National Science Foundation under grant MRI-0923389.
• Douglas, E. S. (2013). Retrieving Leaf Area Index and Foliage Profiles Through Voxelized 3-D Forest Reconstruction Using Terrestrial Full-Waveform and Dual-Wavelength Echidna Lidars.
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  Measuring and monitoring canopy biophysical parameters provide a baseline for carbon flux studies related to deforestation and disturbance in forest ecosystems. Terrestrial full-waveform lidar systems, such as the Echidna Validation Instrument (EVI) and its successor Dual-Wavelength Echidna Lidar (DWEL), offer rapid, accurate, and automated characterization of forest structure. In this study, we apply a methodology based on voxelized 3-D forest reconstructions built from EVI and DWEL scans to directly estimate two important biophysical parameters: Leaf Area Index (LAI) and foliage profile. Gap probability, apparent reflectance, and volume associated with the laser pulse footprint at the observed range are assigned to the foliage scattering events in the reconstructed point cloud. Leaf angle distribution is accommodated with a simple model based on gap probability with zenith angle as observed in individual scans of the stand. The DWEL instrument, which emits simultaneous laser pulses at 1064 nm and 1548 nm wavelengths, provides a better capability to separate trunk and branch hits from foliage hits due to water absorption by leaf cellular contents at 1548 nm band. We generate voxel datasets of foliage points using a classification methodology solely based on pulse shape for scans collected by EVI and with pulse shape and band ratio for scans collected by DWEL. We then compare the LAIs and foliage profiles retrieved from the voxel datasets of the two instruments at the same red fir site in Sierra National Forest, CA, with each other and with observations from airborne and field measurements. This study further tests the voxelization methodology in obtaining LAI and foliage profiles that are largely free of clumping effects and returns from woody materials in the canopy. These retrievals can provide a valuable 'ground-truth' validation data source for large-footprint spaceborne or airborne lidar systems retrievals.
• Douglas, E. S. (2013). Separating Leaves from Trunks and Branches with Dual-Wavelength Terrestrial Lidar Scanning: Improving Canopy Structure Characterization in 3-D Space.
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  Leaf area index (LAI) is an important parameter characterizing forest structure, used in models regulating the exchange of carbon, water and energy between the land and the atmosphere. However, optical methods in common use cannot separate leaf area from the area of upper trunks and branches, and thus retrieve only plant area index (PAI), which is adjusted to LAI using an appropriate empirical woody-to-total index. An additional problem is that the angular distributions of leaf normals and normals to woody surfaces are quite different, and thus leafy and woody components project quite different areas with varying zenith angle of view. This effect also causes error in LAI retrieval using optical methods. Full-waveform scans at both the NIR (1064 nm) and SWIR (1548 nm) wavelengths from the new terrestrial Lidar, the Dual-Wavelength Echidna Lidar (DWEL), which pulses in both wavelengths simultaneously, easily separate returns of leaves from trunks and branches in 3-D space. In DWEL scans collected at two different forest sites, Sierra National Forest in June 2013 and Brisbane Karawatha Forest Park in July 2013, the power returned from leaves is similar to power returned from trunks/branches at the NIR wavelength, whereas the power returned from leaves is much lower (only about half as large) at the SWIR wavelength. At the SWIR wavelength, the leaf scattering is strongly attenuated by liquid water absorption. Normalized difference index (NDI) images from the waveform mean intensity at the two wavelengths demonstrate a clear contrast between leaves and trunks/branches. The attached image shows NDI from a part of a scan of an open red fir stand in the Sierra National Forest. Leaves appear light, while other objects are darker.Dual-wavelength point clouds generated from the full waveform data show weaker returns from leaves than from trunks/branches. A simple threshold classification of the NDI value of each scattering point readily separates leaves from trunks and branches and avoids the misclassification of trunk edges as leaves. Such classified waveforms and point clouds can provide gap probabilities of leafy and woody materials separately and thus provide better estimate LAI, thereby characterizing 3-D canopy structure more accurately for use in modeling radiation regimes and terrestrial ecosystems. NDI image (part of a scan here) from waveform mean intensities at the two wavelengths. Azimuth angle in X axis and Zenith angle in Y axis
• Douglas, E. S. (2013). Spectroscopy of PSN J00513484+2943149 in UGC 525.
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  We report that inspection of a low-dispersion optical spectrum (range 370-680 nm) of PSN J00513484+2943149 (CBAT TOCP), obtained in heavy twilight with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Steward Observatory on June 28 UT, shows it to be an aging type-Ia supernova. After correcting for a redshift of 4931 km/s for the assumed host galaxy, UGC 525 (Falco et al. 1999, PASP, 111, 438; via NED), reasonable matches are found with normal SNe Ia at epochs ranging between 40 and 65 days after maximum light, although there is a notable absence of emission in PSN J00513484+2943149 near 5000 Angstrom (attributed to Fe II; Branch et al.
• Douglas, E. S. (2013). Supernova 2013do in UGC 12137 = Psn J22395067+3812443.
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  Additional CCD magnitudes for 2013do: 2013 June 1, [19.0 (Wang and Gao); 17.763, 17.0 (Joseph Brimacombe, Cairns, Australia; 41-cm telescope + infrared filter; bandpass 〉 700 nm; position end figures 50s.65, 43".5; image posted at URL http://www.flickr.com/photos/43846774@N02/9074451038/); 18.253, 18.1 (L. Elenin, Lyubertsy, Russia, and I. Molotov, Moscow; three 150-s images taken remotely with a 0.45-m f/2.8 telescope at the ISON-NM Observatory near Mayhill, NM, USA; position end figures 50s.54 +/- 0".18, 44".8 +/- 0".19; UCAC-4 reference stars; limiting mag about 18.8; image posted at website URL http://spaceobs.org/images/TOCP/PSNJ22395067+3812443-20130618.png); 21.832, 17.2 (Wang and Gao; position end figures 50s.69, 44".3); 22.819, 17.1 (Wang and Gao; position end figures 50s.70, 43".3). A. A. Rachubo and D. C. Leonard, San Diego State University; K. Follette, P. Sheehan, and D. McCarthy, University of Arizona; J. Moustakas, Siena College; V. Bailey, J. Barrows, E. Bosset, E. Buckley, D. Burd, J. Calahan, I. Ceesay, E. Douglas, C. Feeney, T. Fornari, A. Fox, H. Fishwick, H. Gano, C. Green, J. Griggs, K. Hart, S. Hart, K. Hartman, A. Holt, E. Hooper, S. Hume, S. Jaeggli, D. Lesser, M. Kerr, C. Kopans-Johnson, K. Kumar, A. Lackey, S. Laube, E. Marshall, M. Martinez, G. Mehta, K. Melbourne, M. Meshel, C. Myers, E. Puranen, A. Schlingman, W. Schlingman, W. M. Schlingman, K. Shen, N. Stock, C. Stillman, J. Tinker, and B. Whitesell, 2013 Advanced Teen Astronomy Camp, report that inspection of a low-dispersion optical spectrum (range 350-660 nm) of PSN J22395067+3812443 = SN 2013do, obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Steward Observatory on June 26 UT, shows it to be a type-II supernova. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) finds best matches with a number of normal type-IIP supernovae ranging in age from about one to two weeks after maximum light. Adopting the recession velocity for UGC 12137 of 4685 km/s (Wegner et al. 1993, A.J. 105, 1251; via the NASA/IPAC Extragalactic Database), an expansion velocity of 8900 km/s is derived from the position of the H_beta (rest wavelength 486.1 nm) minimum. S. Tinyanont, Harvey Mudd College; Y. Cao, California Institute of Technology; and M. M. Kasliwal, Observatories of the Carnegie Institution and Princeton University, report that spectroscopic observations (range 330-1000 nm) of PSN J22395067+3812443 = SN 2013do were obtained on June 27.27 UT with the Dual Imaging Spectrograph on the 3.5-m ARC telescope at Apache Point Observatory. The spectrum shows prominent H-alpha emission with a P-Cyg profile. The minimum of the H-alpha absorption is at 642.5 nm. Using the redshift z = 0.015627 for UGC 12137 (from Wegner et al. 1993, A.J. 105, 1251; via NED), this corresponds to a velocity of 11000 km/s. Running the SNID software, the spectrum resembles SN 2004et at fifteen days after maximum, indicating that 2013do is a type-II-P supernova.
• Douglas, E. S. (2013). Supernova 2013dq in UGC 525 = Psn J00513484+2943149.
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  S. Howerton, Arkansas City, KS, U.S.A.; A. J. Drake, S. G. Djorgovski, A. Mahabal, M. J. Graham, and R. Williams, California Institute of Technology; J. L. Prieto, Princeton University; M. Catelan, Pontificia Universidad Catolica de Chile; and E. Christensen and S. M. Larson, Lunar and Planetary Laboratory, University of Arizona, report the Catalina Real-time Transient Survey discovery of an apparent supernova in public images from the Catalina Sky Survey (CSS). SN 2013 UT R.A. (2000.0) Decl. Mag. Offset 2013dq June 27.44 0 51 34.84 +29 43 14.9 16.8 4".3 E, 15".6 N The variable was designated PSN J00513484+2943149 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2013dq based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2013dq: Feb. 8.14 UT, [19.5 (CSS); June 28.814, 17.2 (Joseph Brimacombe, Cairns, Australia; 41-cm telescope + infrared filter; bandpass 〉 700 nm; position end figures 35s.02, 13".8; image posted at website URL http://www.flickr.com/photos/43846774@N02/9174594184/). A. A. Rachubo and D. C. Leonard, San Diego State University; K. Follette, P. Sheehan, V. Bailey, and D. McCarthy, University of Arizona; J. Moustakas, Siena College; J. Barrows, E. Bosset, E. Buckley, D. Burd, J. Calahan, I. Ceesay, E. Douglas, C. Feeney, T. Fornari, A. Fox, H. Fishwick, H. Gano, C. Green, J. Griggs, K. Hart, S. Hart, K. Hartman, A. Holt, E. Hooper, S. Hume, S. Jaeggli, D. Lesser, M. Kerr, C. Kopans-Johnson, K. Kumar, A. Lackey, S. Laube, E. Marshall, M. Martinez, G. Mehta, K. Melbourne, M. Meshel, C. Myers, E. Puranen, A. Schlingman, W. Schlingman, W. M. Schlingman, K. Shen, N. Stock, C. Stillman, J. Tinker, and B. Whitesell, 2013 Advanced Teen Astronomy Camp, report that inspection of a low-dispersion optical spectrogram (range 370-680 nm) of PSN J00513484+2943149 = SN 2013dq, obtained in heavy twilight with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Steward Observatory on June 28 UT, shows it to be an aging type-Ia supernova. After correcting for a redshift of 4931 km/s for the assumed host galaxy, UGC 525 (Falco et al. 1999, PASP 111, 438; via NED), reasonable matches are found with normal type-Ia supernovae at epochs ranging between 40 and 65 days after maximum light, although there is a notable absence of emission in 2013dq near 500.0 nm (attributed to Fe II; Branch et al. 2008, PASP 120, 135) that is usually seen at this phase. The most convincing individual spectral match is made with SN 1999gp at 50 days post-maximum (Matheson et al. 2008, A.J. 135, 1598), which exhibited a broad, 1991T-like light-curve (dm15[B] = 0.80; Hicken et al. 2009, Ap.J. 700, 331), a "shallow silicon" maximum-light spectrum (Jha et al. 2000, IAUC 7341; Branch et al. 2009, PASP 121, 238), and somewhat-muted 500.0-nm emission at this phase.
• Elenin, L., Molotov, I., Rachubo, A., Leonard, D., Follette, K., Sheehan, P., McCarthy, D., Moustakas, J., Bailey, V., Barrows, J., Bosset, E., Buckley, E., Burd, D., Calahan, J., Ceesay, I., Douglas, E., Feeney, C., Fornari, T., Fox, A., , Fishwick, H., et al. (2013). Supernova 2013do in UGC 12137 = Psn J22395067+3812443. Central Bureau Electronic Telegrams, 3571, 2.
• Howerton, S., Drake, A., Djorgovski, S., Mahabal, A., Graham, M., Williams, R., Prieto, J., Catelan, M., Christensen, E., Larson, S., Rachubo, A., Leonard, D., Follette, K., Sheehan, P., Bailey, V., McCarthy, D., Moustakas, J., Barrows, J., Bosset, E., , Buckley, E., et al. (2013). Supernova 2013dq in UGC 525 = Psn J00513484+2943149. Central Bureau Electronic Telegrams, 3573, 1.
• Rachubo, A., Leonard, D., Follette, K., Sheehan, P., Bailey, V., McCarthy, D., Moustakas, J., Barrows, J., Bosset, E., Buckley, E., Burd, D., Calahan, J., Ceesay, I., Douglas, E., Feeney, C., Fornari, T., Fox, A., Fishwick, H., Gano, H., , Green, C., et al. (2013). Spectroscopy of PSN J00513484+2943149 in UGC 525. The Astronomer's Telegram, 5176, 1.
• Abadie, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Arain, M., Araya, M., Aronsson, M., , Arun, K., et al. (2012). Publisher's Note: Search for gravitational waves from compact binary coalescence in LIGO and Virgo data from S5 and VSR1 [Phys. Rev. D 82, 102001 (2010)]. \prd, 85(8), 089903.
• Abadie, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Arain, M., Araya, M., Aronsson, M., , Aso, Y., et al. (2012). Erratum: Search for gravitational waves from binary black hole inspiral, merger, and ringdown [Phys. Rev. D 83, 122005 (2011)]. \prd, 86(6), 069903.
• Abadie, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Arain, M., Araya, M., Aronsson, M., , Aso, Y., et al. (2012). Publisher's Note: Search for gravitational waves from binary black hole inspiral, merger, and ringdown [Phys. Rev. D 83, 122005 (2011)]. \prd, 85(8), 089904.
• Abadie, J., Abbott, B., Abbott, T., Abbott, R., Abernathy, M., Adams, C., Adhikari, R., Affeldt, C., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amariutei, D., Amin, R., Anderson, S., Anderson, W., Arai, K., Arain, M., Araya, M., , Aston, S., et al. (2012). Implications for the Origin of GRB 051103 from LIGO Observations. \apj, 755(1), 2.
• Douglas, E. S. (2012). A Dual Wavelength Echidna® Lidar (DWEL) for Forest Structure Retrieval.
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  A newly-constructed, ground-based lidar scanner designed for automated retrieval of forest structure, the Dual Wavelength Echidna Lidar (DWEL), separates laser "hits" of leaves from hits of trunks and branches using simultaneous laser pulses at 1548 nm, where leaf water content produces strong absorption, and at 1064 nm, where leaves and branches have similar reflectances. The DWEL uses a rotating mirror scan mechanism on a revolving mount, coupled with full digitization of return waveforms, to identify, locate, and parameterize scattering events in the three-dimensional space around the scanner. In the DWEL instrument, the two measurement lasers are triggered simultaneously. Laser pulses are sharply peaked; full-width half-max pulse length of the lasers is 5.1 ns, corresponding to 1.53 m in distance. The laser pulses are expanded and collimated to a 6-mm beam diameter (1/e2), then shaped into a top-hat cross section using a diffraction apparatus. Interchangeable optics provide a beam divergence of 1.25-, 2.5-, or 5-mrad. A mirror and two dichroic filters combine the beams and join them with a visible green continuous-wave marker laser. The combined beam is guided along an optical path to the 10-cm rotating scan mirror. Scan encoders in zenith and azimuth directions resolve the pointing of the instrument to 215 units per 2π radians. Scan resolution has three settings: 1-, 2-, and 4-mrad. Scan time varies with resolution: 11 min at 4 mrad; 41 min at 2 mrad; and 2.7 hr at 1 mrad. The return beam enters the 10-cm diameter Newtonian-Nasmyth telescope and is directed to the receiver assembly, which splits the return beam using a dichroic filter and narrowband pass filters. Two 0.5 mm InGaAs photodiodes measure the return signal, which is sampled by two digitizers at 2 gigasamples per second with 10-bit precision. This provides a 7.5-cm sampling of the 1.53 m pulse, allowing very good reconstruction of the return waveform. The designed signal-to-noise ratio is 10:1 (8:1) at 100 m with 0.1 reflectance at 1064 nm (1548 nm). A compact PCI single board computer collects the digital and housekeeping data, which is offloaded in real time via gigabit ethernet to a separate field PC. Instrument weight is 20.4 kg (45 lbs), including high-density lithium ion batteries to meet the power requirement of 115 W. The laser system attains a 3R safety classification, and is eye-safe unless viewed directly within 30 m using optical magnification. First images from the Harvard Forest, Petersham, MA, demonstrate the quality and new information content of DWEL scans. The DWEL was built by the Center for Space Physics and Center for Remote Sensing, Boston University, with the support of the US National Science Foundation under grant MRI-0923389. It is based on the design of the Echidna Validation Instrument (EVI), constructed by Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO), and is a realization of a concept for a scanning lidar with full-waveform digitizing, trademarked Echidna®, developed and patented by CSIRO (US patent 7,187,452, Australian Patent 2002227768, New Zealand Patent 527547, Japanese Patent 4108478 and others).
• Douglas, E. S. (2012). Erratum: Search for gravitational waves from binary black hole inspiral, merger, and ringdown [Phys. Rev. D 83, 122005 (2011)].
• Douglas, E. S. (2012). Evaluation of Ionospheric Densities Using OII 83.4 nm Airglow.
• Douglas, E. S. (2012). Evaluation of ionospheric densities using coincident OII 83.4 nm airglow and the Millstone Hill Radar. Journal of Geophysical Research.
• Douglas, E. S. (2012). Implications for the Origin of GRB 051103 from LIGO Observations.
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  We present the results of a LIGO search for gravitational waves (GWs) associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst (GRB) whose electromagnetically determined sky position is coincident with the spiral galaxy M81, which is 3.6 Mpc from Earth. Possible progenitors for short-hard GRBs include compact object mergers and soft gamma repeater (SGR) giant flares. A merger progenitor would produce a characteristic GW signal that should be detectable at a distance of M81, while GW emission from an SGR is not expected to be detectable at that distance. We found no evidence of a GW signal associated with GRB 051103. Assuming weakly beamed γ-ray emission with a jet semi-angle of 30°, we exclude a binary neutron star merger in M81 as the progenitor with a confidence of 98%. Neutron star-black hole mergers are excluded with 〉99% confidence. If the event occurred in M81, then our findings support the hypothesis that GRB 051103 was due to an SGR giant flare, making it one of the most distant extragalactic magnetars observed to date.
• Douglas, E. S. (2012). Ionospheric Observations with Raids, AN Extensive Comparison of O⁺ 83.4 NM Emission to Ground Based Observations.
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  We demonstrate the response of O+ 83.4 nm emission to ionospheric conditions. This emission, generated by inner shell ionization of neutral O at low altitudes and resonantly scattering off O+ in the F2 region, has unique potential for global, dayside remote sensing of the ionospheric plasma density profile. This method is particularly sensitive to the difficult to observe 'topside' profile above the F2 peak. Observed with the Remote Atmospheric and Ionospheric Detection System (RAIDS) Extreme Ultraviolet Spectrograph on the International Space Station (ISS), limb profiles of 83.4 nm emissions are compared to predicted dayglow emission profiles from a model incorporating ground-based electron density profiles. Periods of conjugacy between an extensive RAIDS data set and many days of ground-based observations by ionosonde and incoherent scatter radar provide a characterization of the sensitivity of the 83.4 nm emission profile to a broad range of ionospheric density profiles. From this new multi-day data set, we present maps of dayside emission profiles, demonstrating the variability of 83.4 nm emission in response to local geophysical variables at low latitudes.
• Douglas, E. S. (2012). Publisher's Note: Search for gravitational waves from binary black hole inspiral, merger, and ringdown [Phys. Rev. D 83, 122005 (2011)].
• Douglas, E. S. (2012). Publisher's Note: Search for gravitational waves from compact binary coalescence in LIGO and Virgo data from S5 and VSR1 [Phys. Rev. D 82, 102001 (2010)].
• Douglas, E., Smith, S., Stephan, A., Cashman, L., Bishop, R., Budzien, S., Christensen, A., Hecht, J., & Chakrabarti, S. (2012). Evaluation of ionospheric densities using coincident OII 83.4 nm airglow and the Millstone Hill Radar. Journal of Geophysical Research (Space Physics), 117(A5), A05331.
• Abadie, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Affeldt, C., Allen, B., Allen, G., Amador Ceron, E., Amariutei, D., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Arai, K., Arain, M., , Araya, M., et al. (2011). Beating the Spin-down Limit on Gravitational Wave Emission from the Vela Pulsar. \apj, 737(2), 93.
• Abadie, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Affeldt, C., Allen, B., Allen, G., Amador Ceron, E., Amariutei, D., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Arai, K., Arain, M., , Araya, M., et al. (2011). Search for Gravitational Wave Bursts from Six Magnetars. \apjl, 734(2), L35.
• Abadie, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Arain, M., Araya, M., Aronsson, M., , Arun, K., et al. (2011). Directional Limits on Persistent Gravitational Waves Using LIGO S5 Science Data. \prl, 107(27), 271102.
• Abadie}, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Arain, M., Araya, M., Aronsson, M., , Aso, Y., et al. (2011). Search for gravitational waves from binary black hole inspiral, merger, and ringdown. \prd, 83(12), 122005.
• Ciabattari, F., Dimai, A., Leonini, S., Leonard, D., Moustakas, J., Swift, B., McCarthy, D., Bailey, V., Carrico, E., Carter, A., Chui, E., Douglas, E., Eggeman, E., Goldberg, R., Grant, R., Hartman, K., Hellerstein, J., Hooper, E., Horlick-Cruz, C. .., , Hunter, L., et al. (2011). Supernova 2011dv in NGC 6078 = Psn J16120400+1412330. Central Bureau Electronic Telegrams, 2755, 1.
• Douglas, E. S. (2011). Beating the Spin-down Limit on Gravitational Wave Emission from the Vela Pulsar.
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  We present direct upper limits on continuous gravitational wave emission from the Vela pulsar using data from the Virgo detector's second science run. These upper limits have been obtained using three independent methods that assume the gravitational wave emission follows the radio timing. Two of the methods produce frequentist upper limits for an assumed known orientation of the star's spin axis and value of the wave polarization angle of, respectively, 1.9 × 10-24 and 2.2 × 10-24, with 95% confidence. The third method, under the same hypothesis, produces a Bayesian upper limit of 2.1 × 10-24, with 95% degree of belief. These limits are below the indirect spin-down limit of 3.3 × 10-24 for the Vela pulsar, defined by the energy loss rate inferred from observed decrease in Vela's spin frequency, and correspond to a limit on the star ellipticity of ~10-3. Slightly less stringent results, but still well below the spin-down limit, are obtained assuming the star's spin axis inclination and the wave polarization angles are unknown.
• Douglas, E. S. (2011). Directional Limits on Persistent Gravitational Waves Using LIGO S5 Science Data.
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  The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10-50strain2Hz-1 and 5-35×10-49strain2Hz-1sr-1 for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10-25 in the most sensitive frequency range near 160 Hz.
• Douglas, E. S. (2011). Erratum: "Measurement of SiO₂/InZnGaO₄ heterojunction band offsets by x-ray photoelectron spectroscopy" [Appl. Phys. Lett. 98, 242110 (2011)].
• Douglas, E. S. (2011). Search for Gravitational Wave Bursts from Six Magnetars.
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  Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely ~1 kpc from Earth, an order of magnitude closer than magnetars targeted in previous GW searches. A second, AXP 1E 1547.0-5408, gave a burst with an estimated isotropic energy 〉1044 erg which is comparable to the giant flares. We find no evidence of GWs associated with a sample of 1279 electromagnetic triggers from six magnetars occurring between 2006 November and 2009 June, in GW data from the LIGO, Virgo, and GEO600 detectors. Our lowest model-dependent GW emission energy upper limits for band- and time-limited white noise bursts in the detector sensitive band, and for f-mode ringdowns (at 1090 Hz), are 3.0 × 1044 d 2 1 erg and 1.4 × 1047 d 2 1 erg, respectively, where d_{1} = \frac{d_{{0501}}}{1\,{kpc}} and d 0501 is the distance to SGR 0501+4516. These limits on GW emission from f-modes are an order of magnitude lower than any previous, and approach the range of electromagnetic energies seen in SGR giant flares for the first time.
• Douglas, E. S. (2011). Search for gravitational waves from binary black hole inspiral, merger, and ringdown.
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  We present the first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1-99M☉ and total masses of 25-100M☉. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for 19M☉≤m1, m2≤28M☉ binary black-hole systems with negligible spin to be no more than 2.0Mpc-3Myr-1 at 90% confidence.
• Douglas, E. S. (2011). Spectroscopy of PSN J19583553+0236163.
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  As part of the 2011 Advanced Teen Astronomy Camp (http://www.astronomycamp.org), we obtained a low dispersion optical spectrum (range 370-690 nm) of PSN J19583553+0236163 in UGC 11501 with the 2.3m Bok telescope (+ Boller & Chivens spectrograph) at Steward Observatory, on 2011 June 23 UT. Cross-correlation with a library of supernova spectra using the Supernova Identification code (SNID; Blondin and Tonry 2007, Ap.J.
• Douglas, E. S. (2011). Supernova 2011dn in UGC 11501 = Psn J19583553+0236163.
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  Additional unfiltered CCD magnitudes for SN 2011dn: June 23.23-23.30 UT, 16.5 (R. A. Koff, Bennett, CO, U.S.A.; Celestron 0.20-m f/10 reflector + SBIG ST-6 CCD camera; multiple co-added images); 23.354, 16.1 (Joseph Brimacombe, Cairns, Australia; three co-added 60-s images; position end figures 35s.56, 11".3). Brimacombe's image is posted at the following website URL: http://www.flickr.com/photos/43846774@N02/5865118910/. D. C. Leonard, San Diego State University; J. Moustakas, University of California at San Diego; B. J. Swift and D. McCarthy, University of Arizona; V. Bailey, E. Carrico, A. Carter, E. Chui, E. Douglas, E. Eggeman, R. Goldberg, R. Grant, K. Hartman, J. Hellerstein, E. Hooper, C. Horlick-Cruz, L. Hunter, T. Jiles, E. D. Johnson, K. Kumar, L. Lappe, J. Lee, W. Lee, F. Marsh, G. Mehta, P. Miller, R. Rampalli, J. Reed, K. Rice, H. Saldivar, M. Salgado-Flores, A. Schlingman, W. F. Schlingman, W. M. Schlingman, S. Scibelli, K. Sinclair, I. Steincamp, N. Stock, N. Todd, L. L. Aizpuru Vargas, S. Yamanaka, and E. Zachary, 2011 Advanced Teen Astronomy Camp, report that inspection of a low-dispersion optical spectrum (range 370-690 nm) of PSN J19583553+0236163 = SN 2011dn, obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Steward Observatory on June 23 UT, shows it to be a type-Ia supernova of the SN-1991T-like sub-class, several days before maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) finds good matches with pre-maximum (-6.4 +/- 2.7 days) template spectra of SN 1991T, SN 1997br, and SN 1999aa. Adopting the NASA/IPAC Extragalactic Database (NED) recession velocity for UGC 11501 of 7572 km/s (a 21-cm H I line measurement taken from Springob et al. 2005, Ap.J. Suppl. 160, 149), the maximum absorption in the (weak) Si II line (rest 635.5 nm) is blueshifted by approximately 10100 km/s.
• Douglas, E. S. (2011). Supernova 2011dv in NGC 6078 = Psn J16120400+1412330.
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  F. Ciabattari, Borgo a Mozzano, Italy, reports the discovery of a point- like object (mag 16.2) on unfiltered CCD images (limiting magnitude 19.2) obtained on June 28.86 UT with a 0.5-m Newtonian telescope in the course of the Italian Supernovae Search Project, the new object being located at R.A. = 16h12m04s.62, Decl. = +14d12'33".2 (equinox 2000.0; astrometry with respect to UCAC-2 stars), which is 13" west of the center of the galaxy NGC 6078. The variable was designated PSN J16120400+1412330 when posted on the Central Bureau's TOCP webpage and is here designated SN 2011dv based on the spectroscopic confirmation reported below. Additional magnitudes for 2011dv as provided by Ciabattari: 1992 Apr. 30, [20.3 (Palomar Sky Survey, J plate); 1994 June 8, [20.3 (Palomar Sky Survey, F plate); 2010 June, [19.1 (images taken by Ciabattari); 2011 June 29.98 UT, 16.0 (A. Dimai, Cortina d'Ampezzo, Italy; and S. Leonini, Siena, Italy; remotely using the GRAS-7 PlaneWave 43-cm CDK telescope in Spain). D. C. Leonard, San Diego State University; J. Moustakas, University of California at San Diego; B. J. Swift and D. McCarthy, University of Arizona; V. Bailey, E. Carrico, A. Carter, E. Chui, E. Douglas, E. Eggeman, R. Goldberg, R. Grant, K. Hartman, J. Hellerstein, E. Hooper, C. Horlick-Cruz, L. Hunter, T. Jiles, E. D. Johnson, K. Kumar, L. Lappe, J. Lee, W. Lee, F. Marsh, G. Mehta, P. Miller, R. Rampalli, J. Reed, K. Rice, H. Saldivar, M. Salgado-Flores, A. Schlingman, W. F. Schlingman, W. M. Schlingman, S. Scibelli, K. Sinclair, I. Steincamp, N. Stock, N. Todd, L. L. Aizpuru Vargas, S. Yamanaka, and E. Zachary, 2011 Advanced Teen Astronomy Camp, report that inspection of a low-dispersion optical spectrum (range 370-690 nm) of PSN J16120400+1412330 = SN 2011dv, obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Steward Observatory on June 30 UT, shows it to be a normal type-Ia supernova near maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) finds good matches with near-maximum (2 +/- 6 days) template spectra of SN 1992A and SN 2002bo. Adopting the NASA/IPAC Extragalactic Database recession velocity for NGC 6078 of 9378 km/s (Falco et al. 1999, PASP 111, 438), the maximum absorption in the Si II line (rest 635.5 nm) is blueshifted by approximately 13600 km/s. D. D. Balam, Dominion Astrophysical Observatory, National Research Council of Canada (NRCC); M. L. Graham, Las Cumbres Observatory Global Telescope, University of California at Santa Barbara; E. Y. Hsiao, Lawrence Berkeley Laboratory; and D. W. E. Green, Harvard University, report that a spectrogram (range 389-725 nm., resolution 0.3 nm) of PSN J16120400+1412330 = SN 2011dv, obtained on June 30.27 UT with the 1.82-m Plaskett Telescope of the NRCC, shows it to be a type-Ia supernova about five days past maximum light. Cross-correlation with a library of supernova spectra using the SNID code indicates that 2011dv is most similar to the type-Ia supernova 2006gz at five days past maximum light.
• Douglas, E. S. (2011). Supernova 2011dw in PGC 58436 = PSN J16313945+4129229..
• Douglas, E. S. (2011). Supernova 2011dw in Pgc 58436 = Psn J16313945+4129229.
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  A. Pelloni, J. Newton, and T. Puckett report the discovery of an apparent supernova (mag 17.5) on an unfiltered CCD image (limiting mag 19.0) taken with a 0.35-m reflector at Portal, AZ, U.S.A., on June 24.3395 UT in the course of the Puckett Observatory Supernova Search. The new object, which was confirmed at mag 16.9 on June 27.3391 by Puckett with the 40-cm reflector at Portal, is located at R.A. = 16h31m39.45 Decl. = +41o29'22".9 (equinox 2000.0), which is 17".3 east and 14".0 south of the center of PGC 58436. Nothing is visible at this position on images taken by Puckett on 2011 June 9 (limiting mag 19.1). The variable was designated PSN J16313945+4129229 when posted on the Central Bureau's TOCP webpage and is here designated SN 2011dw based on the spectroscopic report below. Puckett has posted a finder image for 2011dw at website URL http://possdata.com/PSNJ16313945+4129229.jpg. D. C. Leonard, San Diego State University; J. Moustakas, University of California at San Diego; B. J. Swift and D. McCarthy, University of Arizona; V. Bailey, E. Carrico, A. Carter, E. Chui, E. Douglas, E. Eggeman, R. Goldberg, R. Grant, K. Hartman, J. Hellerstein, E. Hooper, C. Horlick-Cruz, L. Hunter, T. Jiles, E. D. Johnson, K. Kumar, L. Lappe, J. Lee, W. Lee, F. Marsh, G. Mehta, P. Miller, R. Rampalli, J. Reed, K. Rice, H. Saldivar, M. Salgado-Flores, A. Schlingman, W. F. Schlingman, W. M. Schlingman, S. Scibelli, K. Sinclair, I. Steincamp, N. Stock, N. Todd, L. L. Aizpuru Vargas, S. Yamanaka, and E. Zachary, 2011 Advanced Teen Astronomy Camp, report that a low-dispersion optical spectrum (range 370-690 nm) of PSN J16313945+4129229 = SN 2011dw, obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Steward Observatory on June 30 UT, displays a featureless, blue continuum. Identifying a faint, unresolved emission line in the spectrum at 675.8 nm with H-alpha indicates a redshift of 0.03, in agreement with the recession velocity reported in the second Sloan Digital Sky Survey Data Release of the putative host galaxy, PGC 58436. The spectrum is reminiscent of a very young type-II/IIb supernova, although additional spectroscopy is required to confirm the nature of this event. Adopting the NASA/IPAC Extragalactic Database distance-modulus estimate of PGC 58436 of m-M = 35.5 magnitudes, that the apparent magnitude of PSN J16313945+4129229 (16.9 on June 27.3391, as reported by the discoverers, above) indicates an absolute magnitude of -18.6, which is a somewhat-greater luminosity than typical type-II/IIb supernovae achieve.
• Douglas, E., Scheurmann, A., Davies, R., Gila, B., Cho, H., Craciun, V., Lambers, E., Pearton, S., & Ren, F. (2011). Erratum: ``Measurement of SiO$_2$/InZnGaO$_4$ heterojunction band offsets by x-ray photoelectron spectroscopy'' [Appl. Phys. Lett. 98, 242110 (2011)]. Applied Physics Letters, 99(5), 059901.
• Koff, R., Leonard, D., Moustakas, J., Swift, B., McCarthy, D., Bailey, V., Carrico, E., Carter, A., Chui, E., Douglas, E., Eggeman, E., Goldberg, R., Grant, R., Hartman, K., Hellerstein, J., Hooper, E., Horlick-Cruz, C. .., Hunter, L., Jiles, T., , Johnson, E., et al. (2011). Supernova 2011dn in UGC 11501 = Psn J19583553+0236163. Central Bureau Electronic Telegrams, 2746, 2.
• Leonard, D., Moustakas, J., Swift, B., McCarthy, D., Bailey, V., Carrico, E., Carter, A., Chui, E., Douglas, E., Eggeman, E., Goldberg, R., Grant, R., Hartman, K., Hellerstein, J., Hooper, E., Horlick-Cruz, C. .., Hunter, L., Jiles, T., Johnson, E., , Kumar, K., et al. (2011). Spectroscopy of PSN J19583553+0236163. The Astronomer's Telegram, 3450, 1.
• Leonard, D., Moustakas, J., Swift, B., McCarthy, D., Bailey, V., Carrico, E., Carter, A., Chui, E., Douglas, E., Eggeman, E., Goldberg, R., Grant, R., Hartman, K., Hellerstein, J., Hooper, E., Horlick-Cruz, C. .., Hunter, L., Jiles, T., Johnson, E., , Kumar, K., et al. (2011). Supernova 2011dn in UGC 11501 = PSN J19583553+0236163.. Central Bureau Electronic Telegrams, 2746, 2.
• Leonard, D., Moustakas, J., Swift, B., McCarthy, D., Bailey, V., Carrico, E., Carter, A., Chui, E., Douglas, E., Eggeman, E., Goldberg, R., Grant, R., Hartman, K., Hellerstein, J., Hooper, E., Horlick-Cruz, C. .., Hunter, L., Jiles, T., Johnson, E., , Kumar, K., et al. (2011). Supernova 2011dv in NGC 6078 = PSN J16120400+1412330.. Central Bureau Electronic Telegrams, 2755, 2.
• Leonard, D., Moustakas, J., Swift, B., McCarthy, D., Bailey, V., Carrico, E., Carter, A., Chui, E., Douglas, E., Eggeman, E., Goldberg, R., Grant, R., Hartman, K., Hellerstein, J., Hooper, E., Horlick-Cruz, C. .., Hunter, L., Jiles, T., Johnson, E., , Kumar, K., et al. (2011). Supernova 2011dw in PGC 58436 = PSN J16313945+4129229.. Central Bureau Electronic Telegrams, 2756, 2.
• Pelloni, A., Newton, J., Puckett, T., Leonard, D., Moustakas, J., Swift, B., McCarthy, D., Bailey, V., Carrico, E., Carter, A., Chui, E., Douglas, E., Eggeman, E., Goldberg, R., Grant, R., Hartman, K., Hellerstein, J., Hooper, E., Horlick-Cruz, C. .., , Hunter, L., et al. (2011). Supernova 2011dw in Pgc 58436 = Psn J16313945+4129229. Central Bureau Electronic Telegrams, 2756, 1.
• Abadie, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Arain, M., Araya, M., Aronsson, M., , Arun, K., et al. (2010). Search for gravitational waves from compact binary coalescence in LIGO and Virgo data from S5 and VSR1. \prd, 82(10), 102001.
• Abadie}, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Aoudia, S., Arain, M., Araya, M., , Aronsson, M., et al. (2010). TOPICAL REVIEW: Predictions for the rates of compact binary coalescences observable by ground-based gravitational-wave detectors. Classical and Quantum Gravity, 27(17), 173001.
• Abadie}, J., Abbott, B., Abbott, R., Abernathy, M., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Arain, M., Araya, M., Aronsson, M., Aso, Y., Aston, S., Atkinson, D., , Aufmuth, P., et al. (2010). Calibration of the LIGO gravitational wave detectors in the fifth science run. Nuclear Instruments and Methods in Physics Research A, 624(1), 223-240.
• Abadie}, J., Abbott, B., Abbott, R., Abernathy, M., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Arain, M., Araya, M., Aronsson, M., Aso, Y., Aston, S., Atkinson, D., , Aufmuth, P., et al. (2010). First Search for Gravitational Waves from the Youngest Known Neutron Star. \apj, 722(2), 1504-1513.
• Collaboration, T., Collaboration, ., Abadie, J., Abbott, B., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Ajith, P., Allen, B., Allen, G., Amador Ceron, E., Amin, R., Anderson, S., Anderson, W., Antonucci, F., Aoudia, S., , Arain, M., et al. (2010). Sensitivity to Gravitational Waves from Compact Binary Coalescences Achieved during LIGO's Fifth and Virgo's First Science Run. arXiv e-prints, arXiv:1003.2481.
• Douglas, E. S. (2010). Calibration of the LIGO gravitational wave detectors in the fifth science run.
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  The Laser Interferometer Gravitational Wave Observatory (LIGO) is a network of three detectors built to detect local perturbations in the space-time metric from astrophysical sources. These detectors, two in Hanford, WA and one in Livingston, LA, are power-recycled Fabry-Perot Michelson interferometers. In their fifth science run (S5), between November 2005 and October 2007, these detectors accumulated one year of triple coincident data while operating at their designed sensitivity. In this paper, we describe the calibration of the instruments in the S5 data set, including measurement techniques and uncertainty estimation.
• Douglas, E. S. (2010). Coordinated investigations of daytime redline optical emissions and incoherent scatter radar measurements from Sondrestromfjord, Greenland.
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  Magnetosphere-ionosphere coupling has been observed via optical emissions, radio and in-situ satellite measurements but much is left to be explored regarding the relation between daytime optical emission and ambient plasma conditions. A particularly useful optical emission for such studies is the atomic oxygen red line at 630nm. The High Resolution Imaging Echelle Spectrograph (HIRISE) instrument allows daytime red line measurement along magnetic longitude from Sondrestromfjord. The mechanisms that contribute to this daytime red line emission at high latitudes are photoelectron impact on atomic oxygen, dissociative recombination, photodissociation of molecular oxygen, collisions of thermal electrons with oxygen atoms, and interaction of incident flux of energetic particles with oxygen. Measurements from HIRISE can be used to characterize the relative importance of these mechanisms and has been previously used to measure optical intensity enhancements coincident with regions of enhanced electron density as measured by Sondrestromfjord incoherent scatter radar (ISR). These measured emissions also show agreement with plasma parameter driven emission models (Pallamraju et al., J. Geophys. Res., 106, 5543-5549, 2001). The work reported here presents HIRISE and ISR data collected simultaneously over multiple days in 2005 and 2006, thereby providing a rich dataset for the comparison of the relative importance of plasma parameters to red line emission intensity.
• Douglas, E. S. (2010). First Search for Gravitational Waves from the Youngest Known Neutron Star.
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  We present a search for periodic gravitational waves from the neutron star in the supernova remnant Cassiopeia A. The search coherently analyzes data in a 12 day interval taken from the fifth science run of the Laser Interferometer Gravitational-Wave Observatory. It searches gravitational-wave frequencies from 100 to 300 Hz and covers a wide range of first and second frequency derivatives appropriate for the age of the remnant and for different spin-down mechanisms. No gravitational-wave signal was detected. Within the range of search frequencies, we set 95% confidence upper limits of (0.7-1.2) × 10-24 on the intrinsic gravitational-wave strain, (0.4-4) × 10-4 on the equatorial ellipticity of the neutron star, and 0.005-0.14 on the amplitude of r-mode oscillations of the neutron star. These direct upper limits beat indirect limits derived from energy conservation and enter the range of theoretical predictions involving crystalline exotic matter or runaway r-modes. This paper is also the first gravitational-wave search to present upper limits on the r-mode amplitude.
• Douglas, E. S. (2010). Search for gravitational waves from compact binary coalescence in LIGO and Virgo data from S5 and VSR1.
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  We report the results of the first search for gravitational waves from compact binary coalescence using data from the Laser Interferometer Gravitational-Wave Observatory and Virgo detectors. Five months of data were collected during the Laser Interferometer Gravitational-Wave Observatory’s S5 and Virgo’s VSR1 science runs. The search focused on signals from binary mergers with a total mass between 2 and 35M☉. No gravitational waves are identified. The cumulative 90%-confidence upper limits on the rate of compact binary coalescence are calculated for nonspinning binary neutron stars, black hole-neutron star systems, and binary black holes to be 8.7×10-3yr-1L10-1, 2.2×10-3yr-1L10-1, and 4.4×10-4yr-1L10-1, respectively, where L10 is 1010 times the blue solar luminosity. These upper limits are compared with astrophysical expectations.
• Douglas, E. S. (2010). Sensitivity to Gravitational Waves from Compact Binary Coalescences Achieved during LIGO's Fifth and Virgo's First Science Run.
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  We summarize the sensitivity achieved by the LIGO and Virgo gravitational wave detectors for compact binary coalescence (CBC) searches during LIGO's fifth science run and Virgo's first science run. We present noise spectral density curves for each of the four detectors that operated during these science runs which are representative of the typical performance achieved by the detectors for CBC searches. These spectra are intended for release to the public as a summary of detector performance for CBC searches during these science runs.
• Douglas, E. S. (2010). TOPICAL REVIEW: Predictions for the rates of compact binary coalescences observable by ground-based gravitational-wave detectors.
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  We present an up-to-date, comprehensive summary of the rates for all types of compact binary coalescence sources detectable by the initial and advanced versions of the ground-based gravitational-wave detectors LIGO and Virgo. Astrophysical estimates for compact-binary coalescence rates depend on a number of assumptions and unknown model parameters and are still uncertain. The most confident among these estimates are the rate predictions for coalescing binary neutron stars which are based on extrapolations from observed binary pulsars in our galaxy. These yield a likely coalescence rate of 100 Myr-1 per Milky Way Equivalent Galaxy (MWEG), although the rate could plausibly range from 1 Myr-1 MWEG-1 to 1000 Myr-1 MWEG-1 (Kalogera et al 2004 Astrophys. J. 601 L179; Kalogera et al 2004 Astrophys. J. 614 L137 (erratum)). We convert coalescence rates into detection rates based on data from the LIGO S5 and Virgo VSR2 science runs and projected sensitivities for our advanced detectors. Using the detector sensitivities derived from these data, we find a likely detection rate of 0.02 per year for Initial LIGO-Virgo interferometers, with a plausible range between 2 × 10-4 and 0.2 per year. The likely binary neutron-star detection rate for the Advanced LIGO-Virgo network increases to 40 events per year, with a range between 0.4 and 400 per year.

Proceedings Publications

• Ashcraft, J. N., Douglas, E. S., Kim, D., Smith, G. A., Cahoy, K., Connors, T., Derby, K. Z., Gasho, V., Gonzales, K., Guthery, C. E., Kim, G. H., Sauve, C., & Serra, P. (2021, aug). The versatile CubeSat Telescope: going to large apertures in small spacecraft. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11819.
• Chung, H., Vargas, C. J., Hamden, E., McMahon, T., Gonzales, K., Khan, A. R., Agarwal, S., Bailey, H., Behroozi, P., Brendel, T., Choi, H., Connors, T., Corlies, L., Corliss, J., Dettmar, R., Dolana, D., Douglas, E. S., Guzman, J., Hamara, D., , Harris, W., et al. (2021, aug). Aspera: the UV SmallSat telescope to detect and map the warm-hot gas phase in nearby galaxy halos. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11819.
• Maier, E. R., Zellem, R. T., Colavita, M., Mennesson, B., Bailey, V. P., Nemati, B., Ygouf, M., & Douglas, E. (2021). Flatfield calibrations with astrophysical sources for the nancy grace roman space telescope's coronagraphic instrument. In American astronomical society meeting abstracts, 53.
• Maier, E., Zellem, R., Colavita, M., Mennesson, B., Bailey, V., Nemati, B., Ygouf, M., & Douglas, E. (2021, jan). Flatfield Calibrations with Astrophysical Sources for the Nancy Grace Roman Space Telescope's Coronagraphic Instrument. In American Astronomical Society Meeting Abstracts, 53.
• Mennesson, B., Bailey, V., Zellem, R., Zimmerman, N., Ygouf, M., Hildebrandt, S., Rhodes, J., Kasdin, J., Macintosh, B., Turnbull, M., Douglas, E., Mandell, A., Nemati, B., Gonzalez, G., Cady, E., Kern, B., Krist, J., Shi, F., Mok, F., , Morrissey, P., et al. (2021, sep). The Roman Space Telescope coronagraph technology demonstration: current status and relevance to future missions. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11823.
• Milani, K., Douglas, E. S., & Ashcraft, J. (2021, aug). Updated simulation tools for Roman coronagraph PSFs. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11819.
• Serra, P., {\v{C}ierny}, O., Kammerer, W., Douglas, E. S., Kim, D. W., Ashcraft, J. N., Smith, G., Guthery, C., Vergoossen, T., Lohrmann, A., Bedington, R., Perumangatt, C., Ling, A., & Cahoy, K. (2021, jun). Optical front-end for a quantum key distribution cubesat. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11852.
• Allan, G., Kang, I., Douglas, E. S., N'Diaye, M., Barbastathis, G., & Cahoy, K. (2020, dec). Deep neural networks to improve the dynamic range of Zernike phase-contrast wavefront sensing in high-contrast imaging systems. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11443.
• Allan, G., Kang, I., Douglas, E. S., N'Diaye, M., Barbastathis, G., & Cahoy, K. (2020, dec). Deep neural networks to improve the dynamic range of {Zernike} phase-contrast wavefront sensing in high-contrast imaging systems. In Space {Telescopes} and {Instrumentation} 2020: {Optical}, {Infrared}, and {Millimeter Wave}, 11443.
• Anugu, N., Morzinski, K. M., Eisner, J., Douglas, E., Marrone, D., Ertel, S., Haffert, S., Montoya, O., Stone, J., Kraus, S., Monnier, J., Lebouquin, J., Berger, J., Woillez, J., & Montarg{\`es}, M. (2020, aug). Betelgeuse scope: single-mode-fibers-assisted optical interferometer design for dedicated stellar activity monitoring. In Interferometry XX, 11490.
• Anugu, N., Morzinski, K., Eisner, J., Douglas, E., & Marrone, D. (2020). Betelgeuse scope: single-mode-fibers-assisted optical interferometer design for dedicated stellar activity monitoring. In Proc. of {SPIE} vol, 11490.
• Ashcraft, J. N., & Douglas, E. S. (2020). An open-source gaussian beamlet decomposition tool for modeling astronomical telescopes. In Modeling, systems engineering, and project management for astronomy {IX}, 11450.
• Ashcraft, J. N., & Douglas, E. S. (2020, dec). An open-source Gaussian beamlet decomposition tool for modeling astronomical telescopes. In Modeling, Systems Engineering, and Project Management for Astronomy IX, 11450.
• Douglas, E. S., Ashcraft, J. N., Belikov, R., Debes, J., Kasdin, J., Krist, J., Lacy, B. I., Nemati, B., Milani, K., Pogorelyuk, L., Riggs, A. E., Savransky, D., & Sirbu, D. (2020, dec). A review of simulation and performance modeling tools for the Roman coronagraph instrument. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11443.
• Douglas, E. S., Ashcraft, J. N., Belikov, R., Debes, J., Kasdin, J., Krist, J., Lacy, B. I., Nemati, B., Milani, K., Pogorelyuk, L., Riggs, A., Savransky, D., & Sirbu, D. (2020, dec). A review of simulation and performance modeling tools for the {Roman} coronagraph instrument. In Space {Telescopes} and {Instrumentation} 2020: {Optical}, {Infrared}, and {Millimeter Wave}, 11443.
• Feng, Y., Ashcraft, J. N., Breckinridge, J. B., Harvey, J. E., Douglas, E. S., Choi, H., Lillie, C., Hull, T., & Kim, D. W. (2020). Topological pupil segmentation and point spread function analysis for large aperture imaging systems. In {AOPC} 2020: {Optics} ultra precision manufacturing and testing, 11568.
• Feng, Y., Ashcraft, J. N., Breckinridge, J. B., Harvey, J. E., Douglas, E. S., Choi, H., Lillie, C., Hull, T., & Kim, D. W. (2020, nov). Topological pupil segmentation and point spread function analysis for large aperture imaging systems. In AOPC 2020: Optics Ultra Precision Manufacturing and Testing, 11568.
• Heath, J., Kupinski, M., Douglas, E., Hart, K., & Breckinridge, J. (2020, dec). Mueller matrix maps of dichroic filters reveal polarization aberrations. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11443.
• Heath, J., Kupinski, M., Douglas, E., Hart, K., & Breckinridge, J. (2020, dec). Mueller matrix maps of dichroic filters reveal polarization aberrations. In Space {Telescopes} and {Instrumentation} 2020: {Optical}, {Infrared}, and {Millimeter Wave}, 11443.
• Jha, A. K., Li, M., Douglas, E. S., Maier, E. R., Omenetto, F. G., & Fucetola, C. (2020, August). Modeling light-controlled actuation of flexible magnetic composite structures using the finite element method ({FEM}). In Molecular and nano machines {III}, 11477.
• Jha, A. K., Li, M., Douglas, E. S., Maier, E. R., Omenetto, F. G., & Fucetola, C. (2020, aug). Modeling light-controlled actuation of flexible magnetic composite structures using the finite element method (FEM). In Molecular and Nano Machines III, 11477.
• Kasdin, N. J., Bailey, V. P., Mennesson, B., Zellem, R. T., Ygouf, M., Rhodes, J., Luchik, T., Zhao, F., Riggs, A. E., Seo, B., Krist, J., Kern, B., Tang, H., Nemati, B., Groff, T. D., Zimmerman, N., Macintosh, B., Turnbull, M., Debes, J., , Douglas, E. S., et al. (2020, dec). The Nancy Grace Roman Space Telescope Coronagraph Instrument (CGI) technology demonstration. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11443.
• Kasdin, N. J., Bailey, V. P., Mennesson, B., Zellem, R. T., Ygouf, M., Rhodes, J., Luchik, T., Zhao, F., Riggs, A., Seo, B., Krist, J., Kern, B., Tang, H., Nemati, B., Groff, T. D., Zimmerman, N., Macintosh, B., Turnbull, M., Debes, J., , Douglas, E. S., et al. (2020, dec). The {Nancy Grace Roman Space Telescope Coronagraph Instrument} ({CGI}) technology demonstration. In Space {Telescopes} and {Instrumentation} 2020: {Optical}, {Infrared}, and {Millimeter Wave}, 11443.
• Maier, E. R., Douglas, E. S., Kim, D. W., Su, K., Ashcraft, J. N., Breckinridge, J. B., Choi, H., Choquet, E., Connors, T. E., Durney, O., Gonzales, K. L., Guthery, C. E., Haughwout, C. A., Heath, J. C., Hyatt, J., Lumbres, J., Males, J. R., Matthews, E. C., Milani, K., , Montoya, O. M., et al. (2020, dec). Design of the vacuum high contrast imaging testbed for CDEEP, the Coronagraphic Debris and Exoplanet Exploring Pioneer. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11443.
• Maier, E. R., Douglas, E. S., Kim, D. W., Su, K., Ashcraft, J. N., Breckinridge, J. B., Choi, H., Choquet, E., Connors, T. E., Durney, O., Gonzales, K. L., Guthery, C. E., Haughwout, C. A., Heath, J. C., Hyatt, J., Lumbres, J., Males, J. R., Matthews, E. C., Milani, K., , Montoya, O. M., et al. (2020, dec). Design of the vacuum high contrast imaging testbed for {CDEEP}, the {Coronagraphic Debris} and {Exoplanet Exploring Pioneer}. In Space {Telescopes} and {Instrumentation} 2020: {Optical}, {Infrared}, and {Millimeter Wave}, 11443.
• Mennesson, B., Juanola-Parramon, R., Nemati, B., Ruane, G., Bailey, V. P., Bolcar, M., Martin, S., Zimmerman, N., Stark, C., Pueyo, L., & others, . (2020, August). Paving the way to future missions: the roman space telescope coronagraph technology demonstration. In arXiv preprint arXiv:2008.05624.
• Milani, K., & Douglas, E. (2020). Faster imaging simulation through complex systems: a coronagraphic example. In Proc. of {SPIE} vol, 11484.
• Milani, K., & Douglas, E. S. (2020, aug). Faster imaging simulation through complex systems: a coronagraphic example. In Optical Modeling and Performance Predictions XI, 11484.
• Morgan, R. E., Allan, G., Douglas, E., Vale Periera, P., Egan, M., Furesz, G., Gubner, J., Haughwout, C., Holden, B., Merk, J., & others, . (2020). Flight integration and testing for the deformable {MirrorDemonstration} mission ({DeMi}) {CubeSat}. In American astronomical society meeting abstracts\# 235, 235.
• Morgan, R., Allan, G., Douglas, E., Vale Periera, P., Egan, M., Furesz, G., Gubner, J., Haughwout, C., Holden, B., Merk, J., Murphy, T., Xin, Y., & Cahoy, K. (2020, jan). Flight Integration and Testing for the Deformable MirrorDemonstration Mission (DeMi) CubeSat. In American Astronomical Society Meeting Abstracts \#235, 235.
• Pereira, P., Holden, B., Morgan, R., Gubner, J., Murphy, T. J., Haughwout, C., Allan, G., Xin, Y., Kammerer, W., Cahoy, K., & others, . (2020, August). Thermomechanical design and testing of the deformable mirror demonstration mission ({DeMi}) {CubeSat}. In AIAA/USU Conference on Small Satellites.
• Stark, C. C., Smith, G. A., Schneider, G., Ruane, G., Pogorelyuk, L., Noenickz, J., N'Diaye, M., Montoya, O. M., Milani, K., Matthews, E. C., Males, J. R., Lumbres, J., Hyatt, J., Heath, J. C., Haughwout, C. A., Guthery, C. E., Gonzales, K. L., Durney, O., Connors, T. E., , Choquet, E., et al. (2020, December). Design of the vacuum high contrast imaging testbed for CDEEP, the Coronagraphic Debris and Exoplanet Imaging Explorer. In Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave (Proc. of the SPIE), 11443.
• Breckinridge, J., Harvey, J., Irvin, R., Chipman, R., Kupinski, M., Davis, J., Kim, D. -., Douglas, E., Lillie, C., & Hull, T. (2019, sep). ExoPlanet Optics: conceptual design processes for stealth telescopes. In UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts IX, 11115.
• Cahoy, K., Clark, J., Douglas, E., Xin, Y., Males, J., Lumbres, J., & Allan, G. (2019, sep). Space-Based Laser Guide Star Mission to Enable Ground and Space Telescope Observations of Faint Objects. In Bulletin of the American Astronomical Society, 51.
• Debes, J., Douglas, E., Ren, B., Nemati, B., Mennesson, B., Poteet, C., Bailey, V., Macintosh, B., Lewis, N., & Chen, C. (2019, jan). Observing Circumstellar Disks with WFIRST/CGI. In American Astronomical Society Meeting Abstracts \#233, 233.
• Douglas, E. S. (2019, January). Diffraction analysis of Laser Guide Star enabled cophasing wavefront control for large segmented aperture space telescopes. In American Astronomical Society Meeting Abstracts #233.
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  Large segmented aperture telescopes such as LUVOIR (Large UV Optical Infrared Surveyor) are in development to achieve the improvement in resolution and contrast necessary to directly image Earth-like exoplanets, in addition to making contributions to general astrophysics. Control of these complex, large optical systems, which may have several dozen meter-sized segments, to a surface precision on the order of picometers is a challenge. A laser guide star (LGS) on a companion spacecraft can provide a 2nd magnitude or brighter source for faster wavefront sensing with a Zernike wavefront sensor than is possible with most natural target stars. We will present feedback control system simulations that show that the LGS can relax the segment stability requirements by up to two orders of magnitude and allow observations of stars with brightnesses unlimited by wavefront sensing considerations. We analyze the approach of using a hexagonal segmented deformable mirror (DM) conjugate to the primary telescope mirror to correct for segment piston, tip, and tilt errors. This control strategy provides a segment wavefront control loop concurrent with Electric Field Conjugation that uses two high actuator count DMs to dig symmetric dark holes. Assuming perfect knowledge and actuation of the system, our preliminary model with an unapodized charge 6 vector vortex coronagraph shows that correcting with the hexagonal DM can significantly improve the contrast achieved by EFC, for example from 3.5*10-7 uncorrected to 6*10-9 with correction for 100 pm RMS of telescope segment error. Dynamic diffraction effects from introducing a typical hexagonal segmented DM result in the residual contrast floor that increases with primary telescope segment error. We present our simulation results and additional analyses of sensitivity to factors such as coronagraph choice and conjugate DM size and segment gap ratio, and discuss strategies for improving the performance of the LGS approach....
• Douglas, E. S. (2019, January). Integration and Testing of the Deformable Mirror Demonstration Mission (DeMi) CubeSat Payload. In American Astronomical Society Meeting Abstracts #233.
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  The Deformable Mirror Demonstration Mission (DeMi) will operate and characterize the on-orbit performance of a Microelectromechanical Systems (MEMS) deformable mirror (DM) with both an image plane and a Shack-Hartmann wavefront sensor (SHWFS). As part of a wavefront sensing and control system for internal coronagraphs on space telescopes, DMs enable exoplanet direct imaging by correcting optical aberrations and speckles due to mechanical, thermal, and optical effects.This talk provides updates on the payload assembly, alignment, calibration, and functional testing prior to integration with the spacecraft. The key DeMi mission requirements are to measure individual DM actuator wavefront displacement contributions to a precision of 12 nm, measure low order optical aberrations to lambda/10 accuracy and lambda/50 precision, and correct static and dynamic wavefront errors to less than 100 nm RMS error. The DeMi MEMS deformable mirror has 140 actuators with 5.5 micron stroke. The optical design contains both an image plane wavefront sensor and a pupil plane SHWFS and enables wavefront sensing from an internal stable laser as well as external stellar sources. Miniaturized high speed controller and driver electronics were developed for DeMi to fit within the CubeSat form factor and use commercially available components. During its planned year of on-orbit operations, the DeMi mission will take PSF measurements of 5 bright stars to demonstrate wavefront control of astrophysical objects in addition to DM characterization tests with the internal light source. A flight-like engineering model of the payload is being integrated and aligned to characterize the engineering DM behavior and calibrate the wavefront sensor sensitivity to poked actuators and low order Zernike modes including tip, tilt, focus, and astigmatism. Next, end-to-end closed loop payload operation tests will be conducted. The flight model will incorporate minor modifications and the testing will be repeated. We will present an overview of the DM/wavefront sensor calibration and operational tests and a discussion of lessons learned....
• Douglas, E. S. (2019, January). Observing Circumstellar Disks with WFIRST/CGI. In American Astronomical Society Meeting Abstracts #233.
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  The Wide Field Infrared Survey Telescope (WFIRST) coronagraphic instrument (CGI) will be capable of directly imaging a wide range of circumstellar disks in a combination of total intensity and polarized visible light, improving on previous high contrast imaging by orders of magnitude. A subsample of cold debris disks previously resolved in scattered light will likely be observed as part of the CGI technology demonstration phase, laying a foundation for the exploration of nearby planetary systems during the remainder of the WFIRST mission. We review the feasibility and potential scientific return for these systems with the expected CGI complement of coronagraphic masks and observing modes, and identify key observations that could be proposed....
• Douglas, E. S. (2019, January). Sensitivity of WFIRST CGI to Exozodiacal Scattered Light. In American Astronomical Society Meeting Abstracts #233.
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  Measuring the surface brightness of visible light scattered by exozodiacal dust is key to understanding the diversity of circumstellar dust populations and optimizing future missions to image rocky exoplanets. The Wide Field Infrared Survey Telescope (WFIRST) coronagraph instrument (CGI) is expected to provide sensitivity to point sources at flux ratios smaller than 5x10^(-8). This opens a new regime of visible light imaging of extended sources, particularly exozodiacal dust, around nearby bright stars. The WFIRST CGI technology demonstration is baselined to include two coronagraph modes with 360 degree dark holes of particular interest for imaging circumstellar dust, a shaped-pupil coronagraph (SPC) with a high-contrast field-of-view from 0.47 arcsec to 1.44 arcsec and a Hybrid-Lyot coronagraph (HLC) from 0.16 arcsec to 0.45 arcsec. We present analytical predictions of the imaging sensitivity to exozodiacal dust using the HLC, in the band from 546 nm to 604 nm, with preliminary estimates exceeding 22 magnitudes per square arcsecond around V = 5 stars. We will also present 2D models used to validate the analytic sensitivity curve by running a range of physically plausible circumstellar disks through an end-to-end instrument model, including the effects of speckles and detector noise from the publicly available WFIRST CGI Observing Scenario 6 simulations....
• Douglas, E. S., Debes, J., Bailey, V., Cahoy, K. L., Krist, J., Lewis, N. K., Mennesson, B., Nemati, B., Ren, B., Xin, Y., & Macintosh, B. (2019, jan). Sensitivity of WFIRST CGI to Exozodiacal Scattered Light. In American Astronomical Society Meeting Abstracts \#233, 233.
• Douglas, E. S., Debes, J., Milani, K., Xin, Y., Cahoy, K. L., Lewis, N. K., & Macintosh, B. (2019, sep). Simulating the effects of exozodiacal dust in WFIRST CGI observations. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11117.
• Douglas, E. S., Debes, J., Milani, K., Xin, Y., Cahoy, K. L., Lewis, N. K., & Macintosh, B. (2019, sep). Simulating the effects of exozodiacal dust in WFIRST CGI observations. In Techniques and Instrumentation for Detection of Exoplanets IX, 11117.
• Douglas, E., Cahoy, K. L., Morgan, R. E., & Knapp, M. (2019, sep). CubeSats for Astronomy and Astrophysics. In Bulletin of the American Astronomical Society, 51.
• Morgan, R. E., Allan, G. W., Douglas, E., Gubner, J. N., Xin, Y., Do, V., Holden, B. G., Haughwout, C. A., Furesz, G., Egan, M., Merk, J., Barnes, D., Opperman, R., & Cahoy, K. L. (2019, jan). Integration and Testing of the Deformable Mirror Demonstration Mission (DeMi) CubeSat Payload. In American Astronomical Society Meeting Abstracts \#233, 233.
• Morgan, R., Allan, G., Douglas, E., Pereira, P., Egan, M., Furesz, G., Gubner, J., Haughwout, C., Holden, B., Merk, J., Murphy, T., Stein, A., Xin, Y., & Cahoy, K. (2019, sep). Optical modeling and testing of the {Deformable Mirror Demonstration Mission} ({DeMi}) {CubeSat} payload. In Astronomical {Optics}: {Design}, {Manufacture}, and {Test} of {Space} and {Ground Systems II}, 11116.
• Morgan, R., Allan, G., Douglas, E., Vale, P. P., Egan, M., Furesz, G., Gubner, J., Haughwout, C., Holden, B., Merk, J., Murphy, T., Stein, A., Xin, Y., & Cahoy, K. (2019, sep). Optical modeling and testing of the Deformable Mirror Demonstration Mission (DeMi) CubeSat payload. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems II, 11116.
• Walker, C., & Douglas, E. (2019, dec). CatSat: Real Time Imaging and Ionospheric Sounding from a CubeSat. In AGU Fall Meeting Abstracts, 2019.
• Xin, Y., Douglas, E., Allan, G. W., Clark, J. R., Guyon, O., Lumbres, J. R., Males, J., & Cahoy, K. L. (2019, jan). Diffraction analysis of Laser Guide Star enabled cophasing wavefront control for large segmented aperture space telescopes. In American Astronomical Society Meeting Abstracts \#233, 233.
• Allan, G., Douglas, E. S., Barnes, D., Egan, M., Furesz, G., Grunwald, W., Gubner, J., Haughwout, C., Holden, B. G., Vale, P. P., Stein, A. J., & Cahoy, K. L. (2018, aug). The deformable mirror demonstration mission (DeMi) CubeSat: optomechanical design validation and laboratory calibration. In Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 10698.
• Clark, J. R., Carlton, A., Douglas, E. S., Males, J. R., Lumbres, J., Feinberg, L., Guyon, O., Marlow, W., & Cahoy, K. L. (2018, jan). Capabilities of a Laser Guide Star for a Large Segmented Space Telescope. In American Astronomical Society Meeting Abstracts \#231, 231.
• Debes, J., Chen, C., Dawson, B., Douglas, E. S., Duchene, G., Jang-Condell, H., hines, D. C., Lewis, N. K., Macintosh, B., Mazoyer, J., Meshkat, T., Nemati, B., Patel, R., Perrin, M., Poteet, C., Pueyo, L., Ren, B., Rizzo, M., Roberge, A., , Stark, C., et al. (2018, jan). WFIRST: CGI Detection and Characterization of Circumstellar Disks. In American Astronomical Society Meeting Abstracts \#231, 231.
• Douglas, E. S. (2018, August). Review of high-contrast imaging systems for current and future ground- and space-based telescopes I: coronagraph design methods and optical performance metrics. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series.
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  The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. In this first installment of a series of three papers summarizing the outcomes of the OOC workshop, we present an overview of design methods and optical performance metrics developed for coronagraph instruments. The design and optimization of coronagraphs for future telescopes has progressed rapidly over the past several years in the context of space mission studies for Exo-C, WFIRST, HabEx, and LUVOIR as well as ground-based telescopes. Design tools have been developed at several institutions to optimize a variety of coronagraph mask types. We aim to give a broad overview of the approaches used, examples of their utility, and provide the optimization tools to the community. Though it is clear that the basic function of coronagraphs is to suppress starlight while maintaining light from off-axis sources, our community lacks a general set of standard performance metrics that apply to both detecting and characterizing exoplanets. The attendees of the OOC workshop agreed that it would benefit our community to clearly define quantities for comparing the performance of coronagraph designs and systems. Therefore, we also present a set of metrics that may be applied to theoretical designs, testbeds, and deployed instruments. We show how these quantities may be used to easily relate the basic properties of the optical instrument to the detection significance of the given point source in the presence of realistic noise....
• Douglas, E. S. (2018, August). The WFIRST coronagraph instrument: a major step in the exploration of sun-like planetary systems via direct imaging. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series.
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  The Wide Field Infrared Survey Telescope (WFIRST) Coronagraph Instrument (CGI) will be the first high-performance stellar coronagraph using active wavefront control for deep starlight suppression in space, providing unprecedented levels of contrast and spatial resolution for astronomical observations in the optical. One science case enabled by the CGI will be taking visible images and (R 50) spectra of faint interplanetary dust structures present in the habitable zone of nearby sunlike stars ( 10 pc) and within the snow-line of more distant ones ( 20 pc), down to dust brightness levels commensurate with that of the solar system zodiacal cloud. Reaching contrast levels below 10-7 at sub-arcsecond angular scales for the first time, CGI will cross an important threshold in debris disks physics, accessing disks with low enough optical depths that their structure is dominated by transport mechanisms rather than collisions. Hence, CGI will help us understand how exozodiacal dust grains are produced and transported in low-density disks around mature stars. Additionally, CGI will be able to measure the brightness level and constrain the degree of asymmetry of exozodiacal clouds around individual nearby sunlike stars in the optical, at the 3x solar zodiacal emission level. This information will be extremely valuable for optimizing the observational strategy of possible future exo-Earth direct imaging missions, especially those planning to operate at optical wavelengths as well, such as the Habitable Exoplanet Observatory (HabEx) and the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR)....
• Douglas, E. S. (2018, August). The deformable mirror demonstration mission (DeMi) CubeSat: optomechanical design validation and laboratory calibration. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series.
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  Coronagraphs on future space telescopes will require precise wavefront correction to detect Earth-like exoplanets near their host stars. High-actuator count microelectromechanical system (MEMS) deformable mirrors provide wavefront control with low size, weight, and power. The Deformable Mirror Demonstration Mission (DeMi) payload will demonstrate a 140 actuator MEMS Deformable Mirror (DM) with 5:5 μm maximum stroke. We present the flight optomechanical design, lab tests of the flight wavefront sensor and wavefront reconstructor, and simulations of closed-loop control of wavefront aberrations. We also present the compact flight DM controller, capable of driving up to 192 actuator channels at 0-250V with 14-bit resolution. Two embedded Raspberry Pi 3 compute modules are used for task management and wavefront reconstruction. The spacecraft is a 6U CubeSat (30 cm x 20 cm x 10 cm) and launch is planned for 2019....
• Douglas, E. S. (2018, January). WFIRST: CGI Detection and Characterization of Circumstellar Disks. In American Astronomical Society Meeting Abstracts #231.
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  The WFIRST Coronagraphic Instrument (CGI) will be capable of obtaining up to 5×10-9 contrast to an inner working angle of ~150 mas for a selection of medium band visible light filters using shaped pupil coronagraph and hybrid Lyot coronagraph designs. We present initial work at defining the scientific capabilities of the CGI with respect to different types of circumstellar disks, including warm exo-zodiacal disks, cold debris disks, and protoplanetary disks. With the above designs, CGI will be able to detect bright protoplanetary and debris disks with sizes of >100 AU beyond 500 pc. Additionally, it will be able to discover warm exozodiacal dust disks ten times more massive than that of the Solar System for over 100 nearby solar-type stars. Finally, it will be able to characterize resolved circumstellar dust disks in multiple filters of visible light, providing constraints on the size, shape, and composition of the dust.
• Douglas, E. S. (2018, July). Accelerated modeling of near and far-field diffraction for coronagraphic optical systems. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series.
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  Accurately predicting the performance of coronagraphs and tolerancing optical surfaces for high-contrast imaging requires a detailed accounting of diffraction effects. Unlike simple Fraunhofer diffraction modeling, near and farfield diffraction effects, such as the Talbot effect, are captured by plane-to-plane propagation using Fresnel and angular spectrum propagation. This approach requires a sequence of computationally intensive Fourier transforms and quadratic phase functions, which limit the design and aberration sensitivity parameter space which can be explored at high-fidelity in the course of coronagraph design. This study presents the results of optimizing the multi-surface propagation module of the open source Physical Optics Propagation in PYthon (POPPY) package. This optimization was performed by implementing and benchmarking Fourier transforms and array operations on graphics processing units, as well as optimizing multithreaded numerical calculations using the NumExpr python library where appropriate, to speed the end-to-end simulation of observatory and coronagraph optical systems. Using realistic systems, this study demonstrates a greater than five-fold decrease in wall-clock runtime over POPPY's previous implementation and describes opportunities for further improvements in diffraction modeling performance....
• Douglas, E. S. (2018, July). MagAO-X: project status and first laboratory results. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series.
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  MagAO-X is an entirely new extreme adaptive optics system for the Magellan Clay 6.5 m telescope, funded by the NSF MRI program starting in Sep 2016. The key science goal of MagAO-X is high-contrast imaging of accreting protoplanets at Hα. With 2040 actuators operating at up to 3630 Hz, MagAO-X will deliver high Strehls (> 70%), high resolution (19 mas), and high contrast (< 1 × 10-4 ) at Hα (656 nm). We present an overview of the MagAO-X system, review the system design, and discuss the current project status....
• Douglas, E. S. (2018, July). Modeling coronagraphic extreme wavefront control systems for high contrast imaging in ground and space telescope missions. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series.
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  The challenges of high contrast imaging (HCI) for detecting exoplanets for both ground and space applications can be met with extreme adaptive optics (ExAO), a high-order adaptive optics system that performs wavefront sensing (WFS) and correction at high speed. We describe 2 ExAO optical system designs, one each for ground- based telescopes and space-based missions, and examine them using the angular spectrum Fresnel propagation module within the Physical Optics Propagation in Python (POPPY) package. We present an end-to-end (E2E) simulation of the MagAO-X instrument, an ExAO system capable of delivering 6x10-5 visible-light raw contrast for static, noncommon path aberrations without atmosphere. We present an E2E simulation of a laser guidestar (LGS) companion spacecraft testbed demonstration, which uses a remote beacon to increase the signal available for WFS and control of the primary aperture segments of a future large space telescope, providing of order 10 factor improvement for relaxing observatory stability requirements....
• Douglas, E. S. (2018, July). Surveying the Epsilon Eridani system Using MagAO. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series.
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  The Epsilon Eridani system is a star system 10 ly away predicted to be similar to our solar system, making it a particularly interesting target for exoplanet detection. A Jupiter-like exoplanet has been predicted at 1.88 arcsec using radial velocity techniques, and an outer debris disk has been imaged at 35 - 90 AU with Spitzer and CSO observations. We present a preliminary survey of the inner system using the MagAO instrument with the Magellan Clay telescope in Chile. We apply and evaluate the Karhunen-Loeve Image Projection technique, which estimates the point spread function (PSF) of the central star for high-contrast imaging using Principal Component Analysis (PCA). We perform this analysis by adapting the pyKLIP package, which was developed for analyzing data from the Gemini Planet Imager instrument, to be used with data from the MagAO/VisAO instrument....
• Douglas, E. S. (2018, July). WFIRST coronagraph technology requirements: status update and systems engineering approach. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series.
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  The Coronagraph Instrument (CGI) on the Wide-Field Infrared Survey Telescope (WFIRST) will demonstrate technologies and methods for high-contrast direct imaging and spectroscopy of exoplanet systems in reflected light, including polarimetry of circumstellar disks. The WFIRST management and CGI engineering and science investigation teams have developed requirements for the instrument, motivated by the objectives and technology development needs of potential future flagship exoplanet characterization missions such as the NASA Habitable Exoplanet Imaging Mission (HabEx) and the Large UV/Optical/IR Surveyor (LUVOIR). The requirements have been refined to support recommendations from the WFIRST Independent External Technical/Management/Cost Review (WIETR) that the WFIRST CGI be classified as a technology demonstration instrument instead of a science instrument. This paper provides a description of how the CGI requirements flow from the top of the overall WFIRST mission structure through the Level 2 requirements, where the focus here is on capturing the detailed context and rationales for the CGI Level 2 requirements. The WFIRST requirements flow starts with the top Program Level Requirements Appendix (PLRA), which contains both high-level mission objectives as well as the CGI-specific baseline technical and data requirements (BTR and BDR, respectively). Captured in the WFIRST Mission Requirements Document (MRD), the Level 2 CGI requirements flow from the PLRA objectives, BTRs, and BDRs. There are five CGI objectives in the WFIRST PLRA, which motivate the four baseline technical/data requirements. There are nine CGI level 2 (L2) requirements presented in this work, which have been developed and validated using predictions from increasingly refined observatory and instrument performance models. We also present the process and collaborative tools used in the L2 requirements development and management, including the collection and organization of science inputs, an open-source approach to managing the requirements database, and automating documentation. The tools created for the CGI L2 requirements have the potential to improve the design and planning of other projects, streamlining requirement management and maintenance. The WFIRST CGI passed its System Requirements Review (SRR) and System Design Review (SDR) in May 2018. The SRR examines the functional requirements and performance requirements defined for the system and the preliminary program or project plan and ensures that the requirements and the selected concept will satisfy the mission, and the SDR examines the proposed system architecture and design and the flow down to all functional elements of the system...
• Douglas, E. S., & Perrin, M. D. (2018, jul). Accelerated modeling of near and far-field diffraction for coronagraphic optical systems. In Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 10698.
• Douglas, E. S., Carlton, A. K., Cahoy, K. L., Kasdin, N. J., Turnbull, M., & Macintosh, B. (2018, jul). WFIRST coronagraph technology requirements: status update and systems engineering approach. In Modeling, Systems Engineering, and Project Management for Astronomy VIII, 10705.
• Douglas}, E. S., Cahoy, K., Carlton, A., Macintosh, B., Turnbull, M., Kasdin, J., & Teams, {. (2018, jan). WFIRST: Update on the Coronagraph Science Requirements. In American Astronomical Society Meeting Abstracts \#231, 231.
• Grunwald, W., Holden, B., Barnes, D., Allan, G., Mehrle, N., Douglas, E. S., & Cahoy, K. (2018, jan). DeMi Payload Progress Update and Adaptive Optics (AO) Control Comparisons - Meeting Space AO Requirements on a CubeSat. In American Astronomical Society Meeting Abstracts \#231, 231.
• Lumbres, J., Males, J., Douglas, E., Close, L., Guyon, O., Cahoy, K., Carlton, A., Clark, J., Doelman, D., Feinberg, L., Knight, J., Marlow, W., Miller, K., Morzinski, K., Por, E., Rodack, A., Schatz, L., Snik, F., Van, G. K., & Wilby, M. (2018, jul). Modeling coronagraphic extreme wavefront control systems for high contrast imaging in ground and space telescope missions. In Adaptive Optics Systems VI, 10703.
• Males, J. R., Close, L. M., Miller, K., Schatz, L., Doelman, D., Lumbres, J., Snik, F., Rodack, A., Knight, J., Van, G. K., Long, J. D., Hedglen, A., Kautz, M., Jovanovic, N., Morzinski, K., Guyon, O., Douglas, E., Follette, K. B., Lozi, J., , Bohlman, C., et al. (2018, jul). MagAO-X: project status and first laboratory results. In Adaptive Optics Systems VI, 10703.
• Mennesson, B., Debes, J., Douglas, E., Nemati, B., Stark, C., Kasdin, J., Macintosh, B., Turnbull, M., Rizzo, M., Roberge, A., Zimmerman, N., Cahoy, K., Krist, J., Bailey, V., Trauger, J., Rhodes, J., Moustakas, L., Frerking, M., Zhao, F., , Poberezhskiy, I., et al. (2018, aug). The WFIRST coronagraph instrument: a major step in the exploration of sun-like planetary systems via direct imaging. In Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 10698.
• Morgan, R. E., Douglas, E. S., Cahoy, K. L., Males, J. R., Morzinski, K. M., & Close, L. (2018, jul). Surveying the Epsilon Eridani system Using MagAO. In Adaptive Optics Systems VI, 10703.
• Ruane, G., Riggs, A., Mazoyer, J., Por, E., N'Diaye, M., Huby, E., Baudoz, P., Galicher, R., Douglas, E., Knight, J., Carlomagno, B., Fogarty, K., Pueyo, L., Zimmerman, N., Absil, O., Beaulieu, M., Cady, E., Carlotti, A., Doelman, D., , Guyon, O., et al. (2018, aug). Review of high-contrast imaging systems for current and future ground- and space-based telescopes I: coronagraph design methods and optical performance metrics. In Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 10698.
• Cahoy, K. L., Douglas, E., Carlton, A., Clark, J., & Haughwout, C. (2017, jan). How CubeSats contribute to Science and Technology in Astronomy and Astrophysics. In American Astronomical Society Meeting Abstracts \#229, 229.
• Douglas, E. S. (2017, September). Design of the deformable mirror demonstration CubeSat (DeMi). In Techniques and Instrumentation for Detection of Exoplanets VIII.
• Douglas, E. S. (2017, September). Simulating the WFIRST coronagraph integral field spectrograph. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series.
  More info

  A primary goal of direct imaging techniques is to spectrally characterize the atmospheres of planets around other stars at extremely high contrast levels. To achieve this goal, coronagraphic instruments have favored integral field spectrographs (IFS) as the science cameras to disperse the entire search area at once and obtain spectra at each location, since the planet position is not known a priori. These spectrographs are useful against confusion from speckles and background objects, and can also help in the speckle subtraction and wavefront control stages of the coronagraphic observation. We present a software package, the Coronagraph and Rapid Imaging Spectrograph in Python (crispy) to simulate the IFS of the WFIRST Coronagraph Instrument (CGI). The software propagates input science cubes using spatially and spectrally resolved coronagraphic focal plane cubes, transforms them into IFS detector maps and ultimately reconstructs the spatio-spectral input scene as a 3D datacube. Simulated IFS cubes can be used to test data extraction techniques, refine sensitivity analyses and carry out design trade studies of the flight CGI-IFS instrument. crispy is a publicly available Python package and can be adapted to other IFS designs.
• Douglas, E. S., Allan, G., Barnes, D., Figura, J. S., Haughwout, C. A., Gubner, J. N., Knoedler, A. A., LeClair, S., Murphy, T. J., Skouloudis, N., Merck, J., Opperman, R. A., & Cahoy, K. L. (2017, sep). Design of the deformable mirror demonstration CubeSat (DeMi). In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 10400.
• Douglas, E. S., Bendek, E., Marinan, A., Belikov, R., Merck, J., & Cahoy, K. L. (2017, jan). The DeMi CubeSat: Wavefront Control with a MEMS Deformable Mirror in Space. In American Astronomical Society Meeting Abstracts \#229, 229.
• Rizzo, M. J., Groff, T. D., Zimmermann, N. T., Gong, Q., Mandell, A. M., Saxena, P., McElwain, M. W., Roberge, A., Krist, J., Riggs, A. E., Cady, E. J., Mejia, P. C., Brandt, T., Douglas, E., & Cahoy, K. (2017, sep). Simulating the WFIRST coronagraph integral field spectrograph. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 10400.
• Douglas, E. S., Mendillo, C. B., Cook, T. A., & Chakrabarti, S. (2016, jul). Wavefront sensing in space from the PICTURE-B sounding rocket. In Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 9904.
• Douglas, E. S., Hewasawam, K., Mendillo, C. B., Cahoy, K. L., Cook, T. A., Finn, S. C., Howe, G. A., Kuchner, M. J., Lewis, N. K., Marinan, A. D., Mawet, D., & Chakrabarti, S. (2015, sep). End-to-end simulation of high-contrast imaging systems: methods and results for the PICTURE mission family. In Techniques and Instrumentation for Detection of Exoplanets VII, 9605.
• Geddes, G., Chakrabarti, S., Cook, T., Finn, S., & Douglas, E. (2015, dec). Error Analysis of O+ Density Retrieved from Combined 83.4 nm and 61.7 nm EUV dayglow. In AGU Fall Meeting Abstracts, 2015.
• Mendillo, C. B., Brown, J., Martel, J., Howe, G. A., Hewasawam, K., Finn, S. C., Cook, T. A., Chakrabarti, S., Douglas, E. S., Mawet, D., Guyon, O., Singh, G., Lozi, J., Cahoy, K. L., & Marinan, A. D. (2015, sep). The low-order wavefront sensor for the PICTURE-C mission. In Techniques and Instrumentation for Detection of Exoplanets VII, 9605.
• Cook, T., Cahoy, K. L., Lewis, N., Swain, M. R., Finn, S. C., Mendillo, C. B., Chakrabarti, S., Martel, J., & Douglas, E. S. (2014, jun). Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph. In American Astronomical Society Meeting Abstracts \#224, 224.
• Douglas, E. S., Mendillo, C. B., Hicks, B., Cook, T., Martel, J., Finn, S., Polidan, R. S., & Chakrabarti, S. (2014, jun). Status of the PICTURE Sounding Rocket to Image the Epsilon Eridani Circumstellar Environment. In American Astronomical Society Meeting Abstracts \#224, 224.
• Douglas, E. S., Mendillo, C., Hicks, B., Cook, T., Polidan, R., & Chakrabarti, S. (2014, jan). Modeling of Expected PICTURE Observations of Exozodiacal Dust Around Epsilon Eridani. In American Astronomical Society Meeting Abstracts \#223, 223.
• Geddes, G., Chakrabarti, S., Cook, T., & Douglas, E. (2014, dec). Evaluation of Ionospheric Parameters Obtained by Inverting O II 83.4 nm Dayglow Profiles from RAIDS. In AGU Fall Meeting Abstracts, 2014.
• Mendillo, C. B., Douglas, E. S., Finn, S. C., Hicks, B., Martel, J., Cook, T., & Chakrabarti, S. (2014, jun). Recent Contrast Measurements Made Using the PICTURE Visible Nulling Coronagraph. In American Astronomical Society Meeting Abstracts \#224, 224.
• Schaaf, C., Paynter, I., Saenz, E., Li, Z., Strahler, A., Peri, F., Erb, A., Raumonen, P., Muir, J., Howe, G., Hewawasam, K., Martel, J., Douglas, E., Chakrabarti, S., Cook, T., Schaefer, M., Newnham, G., Jupp, D., Aardt, J., , Kelbe, D., et al. (2014, dec). Using the Rapid-Scanning, Ultra-Portable, Canopy Biomass Lidar (CBL) Alone and In Tandem with the Full-Waveform Dual-Wavelength Echidna$^{\textregistered}$ Lidar (DWEL) to Establish Forest Structure and Biomass Estimates in a Variety of Ecosystems. In AGU Fall Meeting Abstracts, 2014.
• Strahler, A., Li, Z., Schaaf, C., Howe, G., Martel, J., Hewawasam, K., Douglas, E., Chakrabarti, S., Cook, T., Paynter, I., Saenz, E., Wang, Z., Woodcock, C., Jupp, D., Schaefer, M., & Newnham, G. (2014, dec). Structure Measurements of Leaf and Woody Components of Forests with Dual-Wavelength Lidar Scanning Data. In AGU Fall Meeting Abstracts, 2014.
• Douglas, E. S. (2013). Separating leaves from trunks and branches with dual-wavelength terrestrial lidar scanning. In International Geoscience and Remote Sensing Symposium (IGARSS).
• Douglas, E. S. (2013). Studying canopy structure through 3-D reconstruction of point clouds from full-waveform terrestrial lidar. In International Geoscience and Remote Sensing Symposium (IGARSS).
• Howe, G., Hewawasam, K., Strahler, A., Douglas, E., Martel, J., Cook, T., Chakrabarti, S., Li, Z., Schaaf, C., Paynter, I., Saenz, E., Wang, Z., Yang, X., & Erb, A. (2013, dec). Field Deployments of DWEL, A Dual-Wavelength Echidna Lidar. In AGU Fall Meeting Abstracts, 2013.
• Li, Z., Strahler, A., Schaaf, C., Howe, G., Martel, J., Hewawasam, K., Douglas, E., Chakrabarti, S., Cook, T., Paynter, I., Saenz, E., Wang, Z., Yang, X., Yao, T., Zhao, F., Woodcock, C., Jupp, D., Schaefer, M., Culvenor, D., , Newnham, G., et al. (2013, dec). Separating Leaves from Trunks and Branches with Dual-Wavelength Terrestrial Lidar Scanning: Improving Canopy Structure Characterization in 3-D Space. In AGU Fall Meeting Abstracts, 2013.
• Paynter, I., Saenz, E., Peri, F., Schaaf, C., Wang, Z., Erb, A., Yang, Y., Rouhani, S., Liu, Y., Yang, X., Chen, R., Oktay, S., Gontz, A., Douglas, E., Kim, J., Sun, Q., Strahler, A., Li, Z., Aardt, J., , Kelbe, D., et al. (2013, dec). Coastal Applications of the Canopy Biomass Lidar (CBL). In AGU Fall Meeting Abstracts, 2013.
• Schaaf, C., Paynter, I., Saenz, E., Peri, F., Wang, Z., Erb, A., Yang, X., Strahler, A., Li, Z., Aardt, J., Kelbe, D., Romanczyk, P., Cawse-Nicholson, K. .., Krause, K., Leisso, N., Kampe, T., Meier, C., Ritz, C., Chakrabarti, S., , Cook, T., et al. (2013, dec). Canopy Biomass Lidar (CBL) Acquisitions at NEON and TERN Forest Sites. In AGU Fall Meeting Abstracts, 2013.
• Strahler, A., Yang, X., Li, Z., Schaaf, C., Wang, Z., Yao, T., Zhao, F., Saenz, E., Paynter, I., Douglas, E., Chakrabarti, S., Cook, T., Martel, J., Howe, G., Hewawasam, K., Jupp, D., Culvenor, D., Newnham, G., & Lowell, J. (2013, dec). Retrieving Leaf Area Index and Foliage Profiles Through Voxelized 3-D Forest Reconstruction Using Terrestrial Full-Waveform and Dual-Wavelength Echidna Lidars. In AGU Fall Meeting Abstracts, 2013.
• Chakrabarti, S., Christensen, A., Stephan, A., Smith, S., Budzien, S., Bishop, R. L., Douglas, E., & Hecht, J. (2012, jul). Evaluation of Ionospheric Densities Using OII 83.4 nm Airglow. In 39th COSPAR Scientific Assembly, 39.
• Douglas, E. S. (2012). DWEL: A Dual-Wavelength Echidna Lidar for ground-based forest scanning. In International Geoscience and Remote Sensing Symposium (IGARSS).
• Douglas, E., Stephan, A., Bishop, R., Budzien, S., Christensen, A., Hecht, J., & Chakrabarti, S. (2012, dec). Ionospheric Observations with Raids, AN Extensive Comparison of O$^+$ 83.4 NM Emission to Ground Based Observations. In AGU Fall Meeting Abstracts, 2012.
• Strahler, A., Douglas, E., Martel, J., Cook, T., Mendillo, C., Marshall, R., Chakrabarti, S., Schaaf, C., Woodcock, C., Li, Z., Yang, X., Culvenor, D., Jupp, D., Newnham, G., & Lovell, J. (2012, dec). A Dual Wavelength Echidna\textregistered Lidar (DWEL) for Forest Structure Retrieval. In AGU Fall Meeting Abstracts, 2012.
• Douglas, E., Pallamraju, D., & Chakrabarti, S. (2010, dec). Coordinated investigations of daytime redline optical emissions and incoherent scatter radar measurements from Sondrestromfjord, Greenland. In AGU Fall Meeting Abstracts, 2010.

Presentations

• Douglas, E. (2019, 2). Sensitivity of WFIRST CGI to Exozodiacal Scattered Light (And related topics). UMASS Lowell Space Science Seminar,.
• Douglas, E. (2019, 4). CfA Stars & Planets Seminar, Space Observatories of All Sizes on the Path to Reflected Light Imaging of Exoplanets. Harvard Smithsonian Center for Astrophysics.
• Douglas, E. S. (2019, 2). From the lab to space, lessons learned advancing exoplanet imaging technologies on low-cost platforms. MIT Haystack Observatory Colloquium,.
• Douglas, E. S. (2019, 3). High-Contrast Imaging with WFIRST: High-fidelity simulations of Debris Disk and Exoplanet Science Observations. MIT Planetary Lunch Colloquium Series Seminar.
• Douglas, E. S. (2019, 7). Laboratoire d’Astrophysique de Marseille, Marseille, FR, Space Observatories of All Sizes. Taking high contrast imaging from the lab to space,. R&D Seminar.
• Douglas, E. S. (2018, January). Capabilities of a Laser Guide Star for a Large Segmented Space Telescope. AAS.
  More info

  Large segmented mirror telescopes are planned for future space telescope missions such as LUVOIR (Large UV Optical Infrared Surveyor) to enable the improvement in resolution and contrast necessary to directly image Earth-like exoplanets, in addition to making contributions to general astrophysics. The precision surface control of these complex, large optical systems, which may have over a hundred meter-sized segments, is a challenge. Our initial simulations show that imaging a star of 2nd magnitude or brighter with a Zernike wavefront sensor should relax the segment stability requirements by factors between 10 and 50 depending on the wavefront control strategy. Fewer than fifty stars brighter than magnitude 2 can be found in the sky. A laser guide star (LGS) on a companion spacecraft will allow the telescope to target a dimmer science star and achieve wavefront control to the required stability without requiring slew or repointing maneuvers.We present initial results for one possible mission architecture, with a LGS flying at 100,000 km range from the large telescope in an L2 halo orbit, using a laser transmit power of 8 days) for an expenditure of

Others

• Douglas, E., & Ashcraft, J. (2021). douglase/exozodi\_exosims\_sensitivity: paper accepted for publication.
• Matthews, E. C., Burt, J., Carter, A., Crossfield, I., Douglas, E. S., Feng, F., Morley, C., & Phillips, M. W. (2021). A direct detection of the closest Jupiter analog with JWST/MIRI.
• Douglas, E. (2019). douglase/AJ\_LGS\_2018\_PlotsAndFigs: updated figure 9 and added FITS OPD.
• Gaspar, A., Rieke, G., Ballering, N., Beichman, C. A., Douglas, E. S., Leisenring, J. M., Schneider, G., Su, K. Y., & Ygouf, M. (2019). Imaging planetary perturbations in the epsilon Eridani debris disk.
• Douglas, E. S. (2016). Advancing spaceborne tools for the characterization of planetary ionospheres and circumstellar environments.
• Perrin}, M., Long, J., Douglas, E., Sivaramakrishnan, A., Slocum, C.,