pkg/sun/sun_ephparms.F

27f9df093b Oliv*0001 #include "SUN_OPTIONS.h"
                0002
                0003 CBOP
                0004 C     !ROUTINE: SUN_EPHPARMS
                0005
                0006 C     !INTERFACE: ======================================================
                0007       SUBROUTINE SUN_EPHPARMS(
                0008      I                         t,
                0009      O                         xls, gs, xlm, asc )
                0010
                0011 C     !DESCRIPTION:
                0012 C  This subroutine computes ephemeris parameters used by other Mission
                0013 C  Operations routines:  the solar mean longitude and mean anomaly, and
                0014 C  the lunar mean longitude and mean ascending node.  It uses the model
                0015 C  referenced in The Astronomical Almanac for 1984, Section S
                0016 C  (Supplement) and documented and documented in Exact closed-form
                0017 C  geolocation algorithm for Earth survey sensors, by F.S. Patt and
                0018 C  W.W. Gregg, Int. Journal of Remote Sensing, 1993.  These parameters
                0019 C  are used to compute the solar longitude and the nutation in
                0020 C  longitude and obliquity.
                0021 C
                0022 C       Program written by:     Frederick S. Patt
                0023 C                               General Sciences Corporation
                0024 C                               November 2, 1992
                0025
                0026 C     !USES: ===========================================================
                0027       IMPLICIT NONE
                0028
                0029 C     !INPUT PARAMETERS: ===============================================
                0030 C     t :: Time in days since January 1, 2000 at 12 hours UT
                0031       _RL t
                0032
                0033 C     !OUTPUT PARAMETERS: ==============================================
                0034 C     xls :: Mean solar longitude (degrees)
                0035 C     gs  :: Mean solar anomaly (degrees)
                0036 C     xlm :: Mean lunar longitude (degrees)
                0037 C     asc :: Ascending node of mean lunar orbit (degrees)
                0038       _RL xls, gs, xlm, asc
                0039 CEOP
                0040
                0041 #ifdef ALLOW_SUN
                0042
                0043 C  Sun Mean Longitude
                0044       xls = 280.46592 _d 0 + 0.9856473516 _d 0*t
086a45f245 Oliv*0045       xls = MOD(xls,360 _d 0)
27f9df093b Oliv*0046
                0047 C  Sun Mean Anomaly
                0048       gs = 357.52772 _d 0 + 0.9856002831 _d 0*t
086a45f245 Oliv*0049       gs = MOD(gs,360 _d 0)
27f9df093b Oliv*0050
                0051 C  Moon Mean Longitude
                0052       xlm = 218.31643 _d 0 + 13.17639648 _d 0*t
086a45f245 Oliv*0053       xlm = MOD(xlm,360 _d 0)
27f9df093b Oliv*0054
                0055 C  Ascending Node of Moons Mean Orbit
                0056       asc = 125.04452 _d 0 - 0.0529537648 _d 0*t
086a45f245 Oliv*0057       asc = MOD(asc,360 _d 0)
27f9df093b Oliv*0058
                0059 #endif /* ALLOW_SUN */
                0060
                0061       RETURN
                0062       END
                0063