Light Streak Photometry and Streaktools

Abstract The accuracy of photometric calibration has gradually become a limiting factor in various fields of astronomy, limiting the scientific output of a host of research. Calibration using artificial light sources in low Earth orbit remains largely unexplored. Here, we demonstrate that photometric calibration using light sources in low Earth orbit is a viable and competitive alternative/complement to current calibration techniques, and explore the associated ideas and basic theory. We present the publicly available Python code Streaktools as a means to simulate and perform photometric calibration using real and simulated light streaks. Using Streaktools , we perform “pill” aperture photometry on 131 simulated streaks, and Markov chain Monte Carlo based point-spread-function (PSF) model-fitting photometry on 425 simulated streaks in an attempt to recover the magnitude zeropoint of a real exposure of the Dark Energy Camera instrument on the Blanco 4 m telescope. Our results show that calibration using pill photometry is too inaccurate to be useful, but that PSF photometry is able to produce unbiased and accurate (1 σ error = 3.4 mmag) estimates of the zeropoint of a real image in a realistic scenario, with a reasonable light source. This demonstrates that light-streak photometry is a promising alternative and complement to established techniques, which should be explored and tested further.