=== Introduction and Usage ===

This program adds RA_SUN and RA_DEC to an FT2 file indicating the
position of the sun.  These columns can then be used as part of a
filter with gtmktime.  For example:

$> gtmktime scfile="SC00.fits" filter="(DATA_QUAL==1) && (LAT_CONFIG==1)
&& (abs(ROCK_ANGLE)<52) && (angsep(RA,DEC,RA_SUN,DEC_SUN)>ROI)"
outfile="SC00_withSun.fits"

Where RA,DEC is the location of your source of interest and ROI is the
size of your ROI.  This proceedure will remove those times from the
gti when the sun is within your ROI.

The algorithm used for calculating the Sun position is claimed to be
accurate to 0.01 degrees.

You add the columns to your FT2 file by execution

$> sunpos FT2_file_name

The code will overwrite the input so if you might want to make a backup first

=== Compiling the code ===

You first need to have cfitsio installed.  This can be obtained from 

http://heasarc.gsfc.nasa.gov/fitsio/

The location of cfitsio is indicated by the LHEASOFT environment
variable.  Then just type

$> make

and it should compile.