Dr. David H. Curtis Profile

Dr. David H. Curtis

at Air Force Institute of Technology

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Author

Publications (2)

Proceedings Article | 4 October 2024 Presentation + Paper

Shadow imagery initial field testing progress

Douglas Ruyle, David Curtis, Peter McMahon-Crabtree

Proceedings Volume 13149, 1314904 (2024) https://doi.org/10.1117/12.3028014

KEYWORDS: Stars, Telescopes, Satellites, Cameras, Sensors, Shadows, Diffraction, Point spread functions, Image resolution, Photon counting, Synthetic apertures

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Estimating the silhouette of large resident space objects through decreased intensity measurements is an established technique in astronomy. Synthetic Aperture Silhouette Imaging (SASI) applies these concepts using a North-South oriented linear array of hobby telescopes to detect decreased intensity from stars as satellites occult the stars. Within the past twenty years this technique has been expanded to satellites near Earth in mathematical and computer models as well as scaled laboratory demonstrations. Often this technique is discussed in relation to the geostationary (GEO) belt of satellites, but it could also be applied in other orbital regimes (where a linear North-South array configuration is likely non-optimal). Previous work has indicated that orbital ephemeris data may lack sufficient accuracy to reliably plan measurements of actual satellite occultations (using a single telescope). This paper discusses the progress of an initial field test using a single telescope equipped with a photon detector and astronomical camera. The goal is to measure intensity drops from stars when satellites are predicted to pass between the star and the telescope in a ground station. An 11-inch Celestron Rowe-Ackermann-Schmitt Astrograph is mounted on an Astro-Physics 1600GTO mount and equipped with a ThorLabs single photon counting module SPCM50A and ZWO ASI174 camera. The target is the International Space Station (ISS) in hopes that the larger area of the object’s silhouette will overcome uncertainties in the orbital data. This initial field test informs the design of an individual telescope in a SASI array by capturing challenges, limitations and potential solutions. Hardware issues like periodic error in the telescope mount, image focus, and USB overload led to hardware upgrades and substitutions. Environmental conditions impacted the performance of the telescope mount and camera due to the site location limitations. Ephemeris updates make long-term planning difficult, so occultation predictions need to be reassessed as close to the transit time as possible. These and other issues arose during the initial field test, highlighting challenges that need to be overcome to further develop SASI.

Proceedings Article | 6 June 2024 Presentation + Paper

Shadow imagery resolution advantages from multispectral image stacking

Douglas Ruyle, David Curtis, Peter McMahon-Crabtree

Proceedings Volume 13062, 130620A (2024) https://doi.org/10.1117/12.3012879

KEYWORDS: Diffraction, Satellites, Image restoration, Shadows, Stars, Telescopes, Image resolution, Reconstruction algorithms, MATLAB, Cameras

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