Identifying and Measuring Satellite Streaks in DECam Images

TL;DR

This paper presents a workflow for detecting and measuring satellite streaks in DECam images, demonstrating that satellites are detectable but brightness varies, providing a foundation for assessing their impact on astronomy.

Contribution

The study introduces a novel method combining image filtering, Hough Transform detection, and photometry to identify and analyze satellite streaks in archival astronomical images.

Findings

Satellites are consistently detectable in DECam images.

Brightness of satellite streaks varies significantly across object types.

Method faces challenges detecting faint streaks and short-lived glints.

Abstract

The rapid growth of satellite constellations, particularly Starlink, is increasingly affecting ground-based astronomy. In this project, we developed a workflow to detect, identify, and measure the brightness of trails from artificial satellites and other orbiting objects in archival images from the Dark Energy Camera (DECam), available through the NOIRLab Data Archive. We filtered images with visible streaks, retrieved detector-level images, applied the Hough Transform (via satmetrics) to detect and align trails, and performed surface brightness photometry. We also used SatChecker to obtain likely identifications for each trail. Our sample of nine measured streaks includes Starlink satellites, a navigation satellite, a decommissioned science satellite, and a rocket body. Our results show that satellites and other orbiting objects are consistently detectable in DECam images, but their brightness varies significantly, reflecting design and operational differences across object types and models. While the methodology proved effective, detecting faint streaks was challenging, and short-lived glints remain an even harder problem for future work. This proof-of-concept establishes a foundation for larger statistical studies of satellite impacts on astronomical surveys. The code is available at https://github.com/iausathub/reca-streaks