mirror of
https://github.com/eddyem/apogee_control.git
synced 2025-12-06 18:55:11 +03:00
96 lines
2.8 KiB
Fortran
96 lines
2.8 KiB
Fortran
SUBROUTINE sla_ECOR (RM, DM, IY, ID, FD, RV, TL)
|
|
*+
|
|
* - - - - -
|
|
* E C O R
|
|
* - - - - -
|
|
*
|
|
* Component of Earth orbit velocity and heliocentric
|
|
* light time in a given direction (single precision)
|
|
*
|
|
* Given:
|
|
* RM,DM real mean RA, Dec of date (radians)
|
|
* IY int year
|
|
* ID int day in year (1 = Jan 1st)
|
|
* FD real fraction of day
|
|
*
|
|
* Returned:
|
|
* RV real component of Earth orbital velocity (km/sec)
|
|
* TL real component of heliocentric light time (sec)
|
|
*
|
|
* Notes:
|
|
*
|
|
* 1 The date and time is TDB (loosely ET) in a Julian calendar
|
|
* which has been aligned to the ordinary Gregorian
|
|
* calendar for the interval 1900 March 1 to 2100 February 28.
|
|
* The year and day can be obtained by calling sla_CALYD or
|
|
* sla_CLYD.
|
|
*
|
|
* 2 Sign convention:
|
|
*
|
|
* The velocity component is +ve when the Earth is receding from
|
|
* the given point on the sky. The light time component is +ve
|
|
* when the Earth lies between the Sun and the given point on
|
|
* the sky.
|
|
*
|
|
* 3 Accuracy:
|
|
*
|
|
* The velocity component is usually within 0.004 km/s of the
|
|
* correct value and is never in error by more than 0.007 km/s.
|
|
* The error in light time correction is about 0.03s at worst,
|
|
* but is usually better than 0.01s. For applications requiring
|
|
* higher accuracy, see the sla_EVP and sla_EPV routines.
|
|
*
|
|
* Called: sla_EARTH, sla_CS2C, sla_VDV
|
|
*
|
|
* Last revision: 5 April 2005
|
|
*
|
|
* Copyright P.T.Wallace. All rights reserved.
|
|
*
|
|
* 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
|
|
|
|
REAL RM,DM
|
|
INTEGER IY,ID
|
|
REAL FD,RV,TL
|
|
|
|
REAL sla_VDV
|
|
|
|
REAL PV(6),V(3),AUKM,AUSEC
|
|
|
|
* AU to km and light sec (1985 Almanac)
|
|
PARAMETER (AUKM=1.4959787066E8,
|
|
: AUSEC=499.0047837)
|
|
|
|
|
|
|
|
* Sun:Earth position & velocity vector
|
|
CALL sla_EARTH(IY,ID,FD,PV)
|
|
|
|
* Star position vector
|
|
CALL sla_CS2C(RM,DM,V)
|
|
|
|
* Velocity component
|
|
RV=-AUKM*sla_VDV(PV(4),V)
|
|
|
|
* Light time component
|
|
TL=AUSEC*sla_VDV(PV(1),V)
|
|
|
|
END
|