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author | Joseph Hunkeler <jhunkeler@gmail.com> | 2015-03-04 21:21:30 -0500 |
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committer | Joseph Hunkeler <jhunkeler@gmail.com> | 2015-03-04 21:21:30 -0500 |
commit | d54fe7c1f704a63824c5bfa0ece65245572e9b27 (patch) | |
tree | afc52015ffc2c74e0266653eecef1c8ef8ba5d91 /src/slalib/amp.f | |
download | calfuse-d54fe7c1f704a63824c5bfa0ece65245572e9b27.tar.gz |
Initial commit
Diffstat (limited to 'src/slalib/amp.f')
-rw-r--r-- | src/slalib/amp.f | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/src/slalib/amp.f b/src/slalib/amp.f new file mode 100644 index 0000000..6feb570 --- /dev/null +++ b/src/slalib/amp.f @@ -0,0 +1,68 @@ + SUBROUTINE sla_AMP (RA, DA, DATE, EQ, RM, DM) +*+ +* - - - - +* A M P +* - - - - +* +* Convert star RA,Dec from geocentric apparent to mean place +* +* The mean coordinate system is the post IAU 1976 system, +* loosely called FK5. +* +* Given: +* RA d apparent RA (radians) +* DA d apparent Dec (radians) +* DATE d TDB for apparent place (JD-2400000.5) +* EQ d equinox: Julian epoch of mean place +* +* Returned: +* RM d mean RA (radians) +* DM d mean Dec (radians) +* +* References: +* 1984 Astronomical Almanac, pp B39-B41. +* (also Lederle & Schwan, Astron. Astrophys. 134, +* 1-6, 1984) +* +* Notes: +* +* 1) The distinction between the required TDB and TT is +* always negligible. Moreover, for all but the most +* critical applications UTC is adequate. +* +* 2) The accuracy is limited by the routine sla_EVP, called +* by sla_MAPPA, which computes the Earth position and +* velocity using the methods of Stumpff. The maximum +* error is about 0.3 milliarcsecond. +* +* 3) Iterative techniques are used for the aberration and +* light deflection corrections so that the routines +* sla_AMP (or sla_AMPQK) and sla_MAP (or sla_MAPQK) are +* accurate inverses; even at the edge of the Sun's disc +* the discrepancy is only about 1 nanoarcsecond. +* +* 4) Where multiple apparent places are to be converted to +* mean places, for a fixed date and equinox, it is more +* efficient to use the sla_MAPPA routine to compute the +* required parameters once, followed by one call to +* sla_AMPQK per star. +* +* Called: sla_MAPPA, sla_AMPQK +* +* P.T.Wallace Starlink 19 January 1993 +* +* Copyright (C) 1995 Rutherford Appleton Laboratory +*- + + IMPLICIT NONE + + DOUBLE PRECISION RA,DA,DATE,EQ,RM,DM + + DOUBLE PRECISION AMPRMS(21) + + + + CALL sla_MAPPA(EQ,DATE,AMPRMS) + CALL sla_AMPQK(RA,DA,AMPRMS,RM,DM) + + END |