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author | William Joye <wjoye@cfa.harvard.edu> | 2016-11-02 19:16:17 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2016-11-02 19:16:17 (GMT) |
commit | 293057bdd882685f8ddad66bf77196a5853b08da (patch) | |
tree | 22c02c3808f490432f5f785c8bb665438169662b /ast/pal/palSubet.c | |
parent | 87f20cbc44f8f6b53c00c37f89bc134a1f4cf29e (diff) | |
parent | d26ed8388f100a12996c0b92a98040ef2ba7fa8e (diff) | |
download | blt-293057bdd882685f8ddad66bf77196a5853b08da.zip blt-293057bdd882685f8ddad66bf77196a5853b08da.tar.gz blt-293057bdd882685f8ddad66bf77196a5853b08da.tar.bz2 |
Merge commit 'd26ed8388f100a12996c0b92a98040ef2ba7fa8e' as 'ast'
Diffstat (limited to 'ast/pal/palSubet.c')
-rw-r--r-- | ast/pal/palSubet.c | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/ast/pal/palSubet.c b/ast/pal/palSubet.c new file mode 100644 index 0000000..ada122a --- /dev/null +++ b/ast/pal/palSubet.c @@ -0,0 +1,112 @@ +/* +*+ +* Name: +* palSubet + +* Purpose: +* Remove the E-terms from a pre IAU 1976 catalogue RA,Dec + +* Language: +* Starlink ANSI C + +* Type of Module: +* Library routine + +* Invocation: +* void palSubet ( double rc, double dc, double eq, +* double *rm, double *dm ); + +* Arguments: +* rc = double (Given) +* RA with E-terms included (radians) +* dc = double (Given) +* Dec with E-terms included (radians) +* eq = double (Given) +* Besselian epoch of mean equator and equinox +* rm = double * (Returned) +* RA without E-terms (radians) +* dm = double * (Returned) +* Dec without E-terms (radians) + +* Description: +* Remove the E-terms (elliptic component of annual aberration) +* from a pre IAU 1976 catalogue RA,Dec to give a mean place. + +* Authors: +* PTW: Pat Wallace (STFC) +* TIMJ: Tim Jenness (JAC, Hawaii) +* {enter_new_authors_here} + +* Notes: +* Most star positions from pre-1984 optical catalogues (or +* derived from astrometry using such stars) embody the +* E-terms. This routine converts such a position to a +* formal mean place (allowing, for example, comparison with a +* pulsar timing position). + +* See Also: +* Explanatory Supplement to the Astronomical Ephemeris, +* section 2D, page 48. + +* History: +* 2012-02-12(TIMJ): +* Initial version with documentation taken from Fortran SLA +* Adapted with permission from the Fortran SLALIB library. +* {enter_further_changes_here} + +* Copyright: +* Copyright (C) 1995 Rutherford Appleton Laboratory +* Copyright (C) 2012 Science and Technology Facilities Council. +* All Rights Reserved. + +* Licence: +* This program is free software: you can redistribute it and/or +* modify it under the terms of the GNU Lesser General Public +* License as published by the Free Software Foundation, either +* version 3 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 Lesser General Public License for more details. +* +* You should have received a copy of the GNU Lesser General +* License along with this program. If not, see +* <http://www.gnu.org/licenses/>. + +* Bugs: +* {note_any_bugs_here} +*- +*/ + +#include "pal.h" +#include "pal1sofa.h" + +void palSubet ( double rc, double dc, double eq, double *rm, double *dm ) { + double a[3]; /* The E-terms */ + double v[3]; + double f; + int i; + + /* Note the preference for IAU routines */ + + /* Retrieve the E-terms */ + palEtrms( eq, a ); + + /* Spherical to Cartesian */ + eraS2c( rc, dc, v ); + + /* Include the E-terms */ + f = 1.0 + eraPdp( v, a ); + for (i=0; i<3; i++) { + v[i] = f*v[i] - a[i]; + } + + /* Cartesian to spherical */ + eraC2s( v, rm, dm ); + + /* Bring RA into conventional range */ + *rm = eraAnp( *rm ); + +} |