Simultaneous multi-filter photometric characterization of space debris at the Swiss Optical Ground Station and Geodynamics Observatory Zimmerwald

The Astronomical Institute of the University of Bern (AIUB) is performing space debris research for the past 25 years. The main research topics include the search for and the discovery of space debris objects, the build-up and maintenance of a catalogue of space debris orbits, and the physical characterization of debris objects by fusing astrometric,
photometric and spectroscopic data. In particular, all these tasks are performed using data from the AIUB telescopes at the Swiss Optical Ground Station and Geodynamics Observatory Zimmerwald. We will present the results of a space debris characterization campaign performed with the newly installed multipurpose twin sensor consisting of two 40 cm wide-field telescopes. The configuration of this sensor allows using it for three main purposes: the discovery of faint objects due to its aperture and its wide field of view, the follow-up and recovery of cataloged objects, and their characterization as each telescope is equipped with a color filter set. The latter allows for simultaneous observations in two color bands, a prerequisite to derive color indices of rotating or tumbling objects. In this paper, we will present the results of a campaign performed to characterize functional satellites and debris in GEO and MEO regions. Particular attention will be given to defunct GLONASS satellites. This study provides important information regarding the rotational state, the shape, and the surface material of objects. This information may be used to recognize objects when building up and maintaining catalogs, as well as may facilitate the
identification of a candidate parent’s object of fragments. This analysis is performed exploiting the photometric data acquired with sensors of the Zimmerwald observatory.