There is also a background lightcurve from a source free region of the detector. An image is available for each filter used during each observation. These images are sparse arrays and are stored in a compressed form. A light curve exists for each detected source plus the associated background from a source-free box surrounding the source. This is listed as yr.day, where yr is the last two digits of the year and day is the day of the year e.g. day 300 of 1984 is 84.300.
Times are accurate to the nearest second.
The end time of the observation. This includes all dead time effects, interruptions in coverage etc. Offset The offset from the average expected source position in arc min. This parameter is usually 1-4 arc minutes because of a deliberate random offset put in to the pointing to avoid always the same spot on the detector being exposed by the source. The probability of the detection being due to random chance.