Astronomy Will Not Trail Off: Novel Methods for Removing Satellite Trails From Celestial Images (Abstract)

Volume 48 number 2 (2020)

Owen M. Dugan

Stanford Online High School, Academy Hall Floor 2 8853, 415 Broadway, Redwood City, CA 94063; odugan@ohs.stanford.edu

Abstract

(Abstract only) SpaceX’s Starlink satellite network promises world-wide high-speed internet access. With up to 42,000 satellites to be deployed, however, the Starlink satellite network may significantly degrade ground-based astronomical research and imaging due to trails (e.g., light reflections or emissions) from passing satellites. The difficulty of removing the effects of satellite trails on night sky images is recognized because accurately identifying satellite trails is challenging and satellite trails effect not only the brightness measurements of stars they pass in front of but also the brightness measurements of stars in the vicinity of the satellite trails. Novel algorithms were developed and coded to accurately identify and remove satellite trails and reduce their effects on photometry. Platesolving is used to identify stars within an image, and an algorithm is used to determine the radius of each star identified. Identified star brightnesses are replaced with median nearby image brightness values. Satellite trails are identified by examining each possible line traversing the image, with recursive sizing using area interpolation implemented for large images to reduce processing time. Area and/or cubic interpolation is employed to optimize satellite trail modeling. The code returns to the original image with stars, and a Gaussian brightness profile is developed for the satellite trail to account for satellite trail effects across the entire image. The satellite trail is removed by applying the additive inverse of the fitted Gaussian to every pixel in the image. Significant reductions in the effects of satellite trails on images captured using Earth-based equipment are observed while improving image photometric accuracy. Additional novel solutions for preserving star brightnesses directly under the satellite trails are explored.