Function IRCO_SUNLONG Purpose calculate approximate ecliptic longitude of the sun from satcal Author 850927 A.R.W.de Jonge Category IRAS, WORLD COORDINATES File irco.shl Use doubleprecision function IRCO_SUNLONG( satcal ) I integer satcal satcal clock time in ticks Description The routine calculates the approximate ecliptic longitude of the sun from the time given in IRAS satellite clock ticks. The ecliptic longitude of the sun is in radian with reference to the ecliptic of date The accuracy is to about 30 arcsec. Update DK adapted for Gipsy; satcal is now an integer