ETALON spin period determination from kHz SLR data

Using kHz Satellite LASER Ranging (SLR) data of the SLR station Graz only, we determined the spin periods of the two ETALON satellites – launched into high orbits of about 20,000 km – and their spin period increase during 3 years. The determined spin period values and spin period increase rates at 2004-01-01 are: TET1 = 63 s + 0.484 s/year, and TET2 = 65.5 s + 0.401 s/year.