mirror of
https://github.com/eddyem/BTA_lib.git
synced 2025-12-06 10:45:11 +03:00
75 lines
2.2 KiB
Fortran
75 lines
2.2 KiB
Fortran
DOUBLE PRECISION FUNCTION sla_EQEQX (DATE)
|
|
*+
|
|
* - - - - - -
|
|
* E Q E Q X
|
|
* - - - - - -
|
|
*
|
|
* Equation of the equinoxes (IAU 1994, double precision)
|
|
*
|
|
* Given:
|
|
* DATE dp TDB (loosely ET) as Modified Julian Date
|
|
* (JD-2400000.5)
|
|
*
|
|
* The result is the equation of the equinoxes (double precision)
|
|
* in radians:
|
|
*
|
|
* Greenwich apparent ST = GMST + sla_EQEQX
|
|
*
|
|
* References: IAU Resolution C7, Recommendation 3 (1994)
|
|
* Capitaine, N. & Gontier, A.-M., Astron. Astrophys.,
|
|
* 275, 645-650 (1993)
|
|
*
|
|
* Called: sla_NUTC
|
|
*
|
|
* Patrick Wallace Starlink 23 August 1996
|
|
*
|
|
* Copyright (C) 1996 Rutherford Appleton Laboratory
|
|
*
|
|
* License:
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program (see SLA_CONDITIONS); if not, write to the
|
|
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
|
|
* Boston, MA 02111-1307 USA
|
|
*
|
|
*-
|
|
|
|
IMPLICIT NONE
|
|
|
|
DOUBLE PRECISION DATE
|
|
|
|
* Turns to arc seconds and arc seconds to radians
|
|
DOUBLE PRECISION T2AS,AS2R
|
|
PARAMETER (T2AS=1296000D0,
|
|
: AS2R=0.484813681109535994D-5)
|
|
|
|
DOUBLE PRECISION T,OM,DPSI,DEPS,EPS0
|
|
|
|
|
|
|
|
* Interval between basic epoch J2000.0 and current epoch (JC)
|
|
T=(DATE-51544.5D0)/36525D0
|
|
|
|
* Longitude of the mean ascending node of the lunar orbit on the
|
|
* ecliptic, measured from the mean equinox of date
|
|
OM=AS2R*(450160.280D0+(-5D0*T2AS-482890.539D0
|
|
: +(7.455D0+0.008D0*T)*T)*T)
|
|
|
|
* Nutation
|
|
CALL sla_NUTC(DATE,DPSI,DEPS,EPS0)
|
|
|
|
* Equation of the equinoxes
|
|
sla_EQEQX=DPSI*COS(EPS0)+AS2R*(0.00264D0*SIN(OM)+
|
|
: 0.000063D0*SIN(OM+OM))
|
|
|
|
END
|