Characterizing Panoramic SETI astrometric distortion map

Panoramic SETI is an optical observatory optimized for wide-field, high time-resolution astrophysics, capable of monitoring thousands of square degrees of sky on timescales from nanoseconds to seconds, and designed to detect pulsed technosignatures, rare astrophysical transients, and high-energy photon phenomena. Accurate astrometric calibration is essential for the identification of celestial sources in both SETI and transient astrophysics research. In this paper, we develop a methodology to generate optical distortion maps that correct geometric discrepancies between detector pixel coordinates and true sky positions. The resulting distortion maps will enhance the accuracy of astrometric calibration for Panoramic SETI. Using observational data collected at Lick Observatory, we applied time differential imaging to improve image quality and reduce noise in raw images. Star pixel coordinates measured from centroid calculations were transformed to celestial coordinates using gnomonic projection and compared to the star coordinates extracted from the Hipparcos Catalog. Deviations between Hipparcos Catalog coordinates and estimated star coordinates were mapped using 2D linear interpolation techniques. We found that centroid calculations and gnomonic projections can introduce astrometric errors of ± 0.15° (about one-half of a pixel) in the Panoramic SETI 10 × 10° field of view.