The first step is to derive attitude and orbit related quantities through the 'prefilter' task. The satellite attitude information included in the attitude file is interpolated and the NORAD two line elements (TLEs) are propagated to determine satellite ephemeris quantities. This information is used to calculate quantities such as Bright Earth Angle, Sun Angle, Cut off rigidity, etc. The output file of 'prefilter' contains the following default columns : TIME, POSITION, VELOCITY, QUATERNION, POINTING, POLAR, BORESIGHT, SAT_ALT, SAT_LAT, SAT_LON, Z_RA, Z_DEC, Z_ROLL, ELV, BR_EARTH, FOV_FLAG, SUNSHINE, SUN_ANGLE, MOON_ANGLE, RAM_ANGLE, ANG_DIST, COR_SAX, SAA, SAA_TIME. The default output columns are stored in a CALDB file. A different set of columns can be requested by the user via an input file supplied to the program in the parameter 'outcols'. This input file is an ASCII file where column names are listed one per row. The TIME column is mandatory, other columns allowed are: POSITION, VELOCITY, QUATERNION, POINTING, POLAR, BORESIGHT, SAT_ALT, SAT_LAT, SAT_LON, Z_RA, Z_DEC, Z_ROLL, ELV, BR_EARTH, FOV_FLAG, SUNSHINE, SUN_ANGLE, MOON_ANGLE, RAM_ANGLE, ANG_DIST, COR_ASCA, COR_SAX, MCILWAIN_L, SAA, SAA_TIME.
The second step creates a filter file by running the task 'makefilter'. This
uses as input the output from 'prefilter', the housekeeping file, the spacecraft housekeeping
file and a configuration file.
The 'makefilter' configuration file can be an ASCII file or a FITS file and must contain
for each parameter requested the following information:
the parameter name, the name of the FITS file, the name of the extension containing the parameter, the interpolation method, the calibration method, the output parameter name and comments for the corresponding keyword in the output filter file. The interpolation method is used when the value of a specific parameter is not present at given times; the calibration method is applied when some simple numerical manipulations on the input HK parameters is needed. Currently, the default of the interpolation method is set to copy the last known value of that parameter. The calibration method has not been implemented yet.
The default 'makefilter' configuration file is part of CALDB and includes the following columns: ELV, BR_EARTH, COR_SAX, SAA, SAA_TIME, ANG_DIST, FOV_FLAG, DEC, MCILWAIN_L, MOON_ANGLE, RA, RAM_ANGLE, ROLL, SUNSHINE, SUN_ANGLE, CCDTemp, PixGtULD, Vod1, Vod2, Vrd1, Vrd2, Vsub, Vbackjun, Baselin1, Baselin2, SAC_ADERR, SACSTNUMSTARS, STAST_LOSSFCN, SAC_MODESTAT. In addition the task adds the columns TEN_ARCMIN, SETTLED, ACS_SAA, SAFEHOLD. These columns will be included in the output filter file. Moreover the two columns STLOCKFL and STLOCKST are calculated using information from the spacececraft housekeeping file and added to the output filter file.
xrtfilter hdfile=sw00035009011xhd.hk outdir=./ attfile=sw00035009011sat.fits alignfile=/soft/headas/DEVELCALDB/data/swift/mis/bcf/align/swalign20041115v012.fits ranom=110.487 decnom=71.3567 configfile=myconfigure.conf chatter=5