Data granules contain approximately 190 minutes (2 orbits) of data and will include data from the laser reference system, the instrument star tracker, the gyro, the spacecraft star trackers, and the attitude control system.
The data in this product are used to compute the precise pointing for the GLAS laser. It is a multi-file granule. There are six files: LPA, LRS, GYRO, IST, BST, SCPA. The data are derived from the LPA (Laser Pulse Array) and PRAP (Position Rate and Attitude Packet). The LRS and IST data taken from the PRAP are time aligned with laser shots. The BST (Ball Star Tracker) and the ACS (Attitude Control System) data are also extracted from the PRAP but require no time alignment to the LPA.