The FOT Data

Since the FOT data represent the final stage in the data processing from the BeppoSAX SDC, they are more suitable for building the final GRBM archive than the raw data, which, on the other side, have a provisional character.

The FOT data are split in several Observing Periods (OPs): each OP is a set of next Observations with the same target source in the FOV of the observing instruments (NFIs and/or WFCs) and, therefore, with the same satellite attitude in the limit of the pointing accuracy ($\sim$1$^\prime$). There are also OPs with attitude changing with time: during them, at least some of the BeppoSAX instruments slowly slew; these are intermediate OPs between two different normal pointings. The OPs with no slew, with the instruments on target, are said ``normal pointing'', or ``normal''. Usually, the time durations of the normal OPs range from a few $10^3$ s to $10^5$ s. Typically, for the longest OPs, the number of Observations never exceeds 50-55.

Differently from the case of the RAW data, every OP contain some housekeeping files, reporting some fundamental informations about the satellite: the attitude with a time resolution of $0.5$ s and the ephemeris every 1 s. Clearly, these are required to know the positions of given celestial sources with respect to the GRBM units' axes and the position of the Earth within the BeppoSAX frame of reference, respectively.