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EXOSAT LE Housekeeping FITS file

This file contains two binary table extensions.

The Housekeeping FITS file can be used to correct for pointing errors introduced during periods when EXOSAT was operated in star tracking mode 1 (STR1). In this mode the spacecraft attitude was maintained using one star in the star tracker field of view (FOV) and the position of the sun determined using the fine sun sensor (FSS). In STR1 mode a correction to the reference coordinates is needed to account for the roll error in the spacecraft attitude.

Table#1 ATT_MAT

The first three columns ROLL_CORR, PITCH_CORR and YAW_CORR were corrected for Fine Sun Sensor error and 5 arcsec pitch (if after Sep. 15, 1983). The 5 arcsec offset was introduced on this date to overcome an operational problem in the Attitude and Orbit Control Subsystem (AOCS). The next three columns were taken from the Auxiliary Data File. Also included in the header are keywords which were used in performing the Fine Sun Sensor correction.

Table#2 ATT_DEV - contains the departures with time of the spacecraft from the nominal pointing direction. ICFL, ICRS1, SUNPRE, IGAIN and FSS_ROLL are used to correct the attitude matrix when the pointing mode is STR1 (1 guide star + Sun). ROLL, PITCH, YAW, ICFL and ICRS1 are taken from the Housekeeping parameter records. ROLL, PITCH, and YAW are parameters A511, A512 and A513 respectively. ICFL is parameter A529 and ICRS1 is A528.



 
next up previous contents
Next: The House Keeping file Up: EXOSAT RAW LE FITS Previous: The EVENT file header
Leonard Garcia
1999-05-26