First Light Curve Observations from GSOC-operated SMARTnet Telescope Stations with an sCMOS Camera

Abstract

SMARTnet is a network of sensor operators that observe resident space objects, both satellites and space debris, and exchanges the collected data for further processing by each member. The German Space Operations Center is remotely operating three passive-optical robotic telescope stations on the southern hemisphere as part of SMARTnet and has recently switched one of the telescopes’ cameras from a charge-coupled device (CCD) to a scientific complementary metal-oxide-semiconductor (sCMOS) camera to obtain high-cadence light curves of resident space objects. In this paper, we present the first light curve observations of resident space objects obtained with the 50-cm telescope SMART-03-A-ELSA at the SMARTnet telescope station in Chile using an FLI Kepler4040 sCMOS camera. The system is controlled by our own telescope station control software, SMARTies, demonstrating its capability and flexibility in observation modes. We also compare different methods of obtaining brightness estimates, namely fitting a Gaussian and Moffat profile to the brightness distribution, and aperture summation with the aperture informed by the former method. The two targets selected were 2002–040B (NORAD 27509), a satellite in a graveyard orbit, and 2004–050B (NORAD 28546), an upper stage rocket body in geostationary transfer orbit. We analyse the newly obtained light curves for signs of periodicity, extract observable periods where appropriate, and compare these to previously published values. From our uncorrected data, we obtain a synodic rotational period of (68.0±5.5) s for 2004–050B. Further, we show that the Moffat profile is not always a good model for resident space objects, especially towards the edges of the field of view, and that the integral over the Gaussian distribution and aperture summation result in similar results for strong signals, even under these somewhat difficult circumstances.