| 1 | #include "slalib.h"
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| 2 | #include "slamac.h"
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| 3 | void slaAddet ( double rm, double dm, double eq, double *rc, double *dc )
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| 4 | /*
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| 5 | ** - - - - - - - - -
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| 6 | ** s l a A d d e t
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| 7 | ** - - - - - - - - -
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| 8 | **
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| 9 | ** Add the e-terms (elliptic component of annual aberration) to a
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| 10 | ** pre IAU 1976 mean place to conform to the old catalogue convention.
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| 11 | **
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| 12 | ** Given:
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| 13 | ** rm,dm double RA,Dec (radians) without e-terms
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| 14 | ** eq double Besselian epoch of mean equator and equinox
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| 15 | **
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| 16 | ** Returned:
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| 17 | ** *rc,*dc double RA,dec (radians) with e-terms included
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| 18 | **
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| 19 | ** Called:
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| 20 | ** slaEtrms, slaDcs2c, slaDcc2s, slaDranrm, slaDrange
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| 21 | **
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| 22 | ** Explanation:
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| 23 | ** Most star positions from pre-1984 optical catalogues (or
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| 24 | ** derived from astrometry using such stars) embody the
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| 25 | ** e-terms. If it is necessary to convert a formal mean
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| 26 | ** place (for example a pulsar timing position) to one
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| 27 | ** consistent with such a star catalogue, then the RA,Dec
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| 28 | ** should be adjusted using this routine.
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| 29 | **
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| 30 | ** Reference:
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| 31 | ** Explanatory Supplement to the Astronomical Almanac,
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| 32 | ** ed P.K.Seidelmann (1992), page 169.
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| 33 | **
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| 34 | ** Last revision: 25 July 1996
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| 35 | **
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| 36 | ** Copyright P.T.Wallace. All rights reserved.
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| 37 | */
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| 38 | {
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| 39 | double a[3]; /* Elliptic components of annual aberration vector */
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| 40 | double v[3]; /* Cartesian equivalant of RA,Dec */
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| 41 | int i;
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| 42 |
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| 43 |
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| 44 | /* E-terms vector */
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| 45 | slaEtrms ( eq, a );
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| 46 |
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| 47 | /* Spherical to Cartesian */
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| 48 | slaDcs2c ( rm, dm, v );
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| 49 |
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| 50 | /* Include the e-terms */
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| 51 | for ( i=0; i < 3; i++ ) {
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| 52 | v[i] += a[i];
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| 53 | }
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| 54 |
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| 55 | /* Cartesian to spherical */
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| 56 | slaDcc2s ( v, rc, dc );
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| 57 |
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| 58 | /* Bring RA into conventional range */
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| 59 | *rc = slaDranrm ( *rc );
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| 60 | }
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