Self-calibrated Photometry using Open Source Astrometry Tools (SPOSAT)

ABSTRACT: Traditional methods of gathering radiometrically accurate space situational awareness (SSA) photometry data rely on calibration steps that need 10-12 reference star images to be collected in conjunction with the primary collection. The Air Force needs calibration solutions that reduce these timelines and increase sensor throughput. Our proposed solution follows a successful model of combining the best of open source, peer reviewed astrometry tools with government developed analysis and modeling codes to build a cohesive application that performs self-calibrated photometry based on stars serendipitously observed within the field of view. Our proposed SPOSAT (Self-calibrated Photometry using Open Source Astrometry Tools) system leverages an existing interactive analysis framework that guides users through the process of performing source extraction, blind astrometry, and photometric calibration, automating its steps to process SSA imagery and produce calibrated photometry measurements suitable for use by other analysis tools. SPOSAT also will integrate modern star catalogs, including UCAC4 and NOMAD, to inform our astrometry, source/star correlation, and sensor calibration modules, and will use all available metadata from the input images to optimize the astrometry and sensor modeling computations. This working prototype application will lay the groundwork for integration into existing SSA data pipelines in Phase II and beyond. BENEFIT: Techniques developed in this proposal move towards the goal of completely automated photometry, and will be broadly applicable to organizations and individuals operating both astronomical and space situational awareness telescopes. These techniques will allow for the rapid creation of new photometric data pipelines that improve the ability to test and demonstrate new systems, and could eventually be incorporated into extremely mobile sensor platforms. Government, academic, and amateur astronomers will all benefit from a means to automatically produce calibrated photometry measurements, and these developments will dramatically increase the availability of high quality calibrated photometry data for research as well as for validation of state of the art analysis techniques. Incorporating this technology into highly autonomous satellite platforms could benefit builders and users of those systems as well: calibrating photometry onboard can enable the systems to better inform the onboard decision making process, leading to greater autonomy and more effective missions, as well as to improve responsiveness and reduce bandwidth requirements by transmitting only calibrated photometric data to the ground rather than entire image frames.