Table A.1

Example of the log corresponding to 20 trails identified in HST images. The following information is shown: the HST composite observation ID, the instrument, the filter used, the number of individual exposures in which the SSO was identified (N.ex.), the start time of the exposure in which the SSO was first identified (MJD_start, provided in modified Julian days), the end time of the last exposure in which the SSO was identified (MJD_end, provided in modified Julian days), the total exposure time for the trail (texp) – obtained as the sum of the exposure times of all individual exposures in which the trail was identified; it can be different from MJD_end – MJD_start because there were breaks between individual exposures for readout, filter changes etc. – the right ascension (RA) and declination (Dec) for the beginning and for the end of the trail, the total length of the trail, the apparent magnitude in the filter used for the observation (Mag.), and the corresponding asteroid (if it was identified; otherwise, a question mark indicates unidentified objects).