NAME

USAGE

DESCRIPTION

batsurvey-aspect performs temporal filtering of Swift attitude data, for the purpose of BAT survey analysis.

This task uses the "aspect" program to find the median spacecraft pointing direction (which is saved in a file specified by the "outattfile" parameter). It then examines the spacecraft attitude on a sample-by-sample basis, and identifies "bad" pointing episodes. "Bad" pointing is defined as times when the spacecraft pointing direction or roll are farther from the median values by certain thresholds (specified by the "point_toler" and "roll_toler" parameters). The time intervals of "good pointing" are reported in the file identified by the "outgtifile" parameter.

IMPORTANT NOTE: The output attitude file will only be useful for the requested time interval, and not all times. In particular, the output attitude file will be condensed into a single constant spacecraft attitude applicable for the entire time interval.

PARAMETERS

gtifile [filename]

The name of the file which specifies the time interval(s) of interest, as a standard GTI extension. For example, for BAT survey analysis, this file could specify the time interval of one "snapshot."

attfile [filename]

The Swift attitude file which covers the same time range as gtifile.

outattfile [string]

Name of a revised attitude file, which is created by this task. The revised attitude file should be cleaned of transient "bad pointing" episodes. See important note above.

outgtifile [string]

Name of revised good time interval file, which excludes "bad pointing" episodes. A value of "NONE" indicates the file should not be saved.

(med_ra = -999.0) [real] OUTPUT

Upon output, the median pointing right ascension of the requested time interval, in degrees. If an error occurs, a value of -999.0 is stored.

(med_dec = -999.0) [real] OUTPUT

Upon output, the median pointing declination of the requested time interval, in degrees. If an error occurs, a value of -999.0 is stored.

(med_roll = -999.0) [real] OUTPUT

Upon output, the median roll angle of the requested time interval, in degrees. If an error occurs, a value of -999.0 is stored.

(expotot = -1.0) [real] OUTPUT

Upon output, the total exposure of the requested time interval. If an error occurs, then -1.0 is stored.

(expobad = -1.0) [real] OUTPUT

Upon output, the amount of time where "bad pointing" occurred, in seconds. If an error occurs, then -1.0 is stored.

(point_toler = 0.025) [real]

The "bad pointing" threshold radius, in degrees. When the spacecraft pointing is more than "point_toler" degrees from the median pointing direction, it is declared "bad".

(roll_toler = 0.083) [real]

The "bad pointing" threshold in roll, in degrees. When the spacecraft roll is more than "roll_toler" degrees from the median roll angle, it is declared "bad".

(alignfile = "CALDB") [string]

Spacecraft alignment file name, or "CALDB".

(clobber = YES) [boolean]

If the output file already exists, then setting "clobber = yes" will cause it to be overwritten.

(chatter = 2) [integer, 0 - 5]

Controls the amount of informative text written to standard output. Setting chatter = 1 produces a basic summary of the task actions; chatter = 2 (default) additionally prints the task results; chatter = 5 prints debugging information.

(history = YES) [boolean]

Ignored.

EXAMPLES

1. Given a good time interval table named mygti.fits, we are interested in the time interval given by the fourth row of the table. We also enter the spacecraft attitude file (the "sat" file). The resulting revised attitude information is stored in "snapshot4.att". The default pointing tolerances are used.

     batsurvey-aspect gtifile='mygti.fits[#ROW == 4]' \
          attfile=00035025015/auxil/sw00035025015sat.fits \
          outattfile=snapshot4.att

SEE ALSO

batsurvey, aspect

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