| 1 | #include "slalib.h"
|
|---|
| 2 | #include "slamac.h"
|
|---|
| 3 | void slaEg50 ( double dr, double dd, double *dl, double *db )
|
|---|
| 4 | /*
|
|---|
| 5 | ** - - - - - - - -
|
|---|
| 6 | ** s l a E g 5 0
|
|---|
| 7 | ** - - - - - - - -
|
|---|
| 8 | **
|
|---|
| 9 | ** Transformation from B1950.0 'FK4' equatorial coordinates to
|
|---|
| 10 | ** IAU 1958 Galactic coordinates.
|
|---|
| 11 | **
|
|---|
| 12 | ** (double precision)
|
|---|
| 13 | **
|
|---|
| 14 | ** Given:
|
|---|
| 15 | ** dr,dd double B1950.0 'FK4' RA,dec
|
|---|
| 16 | **
|
|---|
| 17 | ** Returned:
|
|---|
| 18 | ** *dl,*db double Galactic longitude and latitude l2,b2
|
|---|
| 19 | **
|
|---|
| 20 | ** (all arguments are radians)
|
|---|
| 21 | **
|
|---|
| 22 | ** Called:
|
|---|
| 23 | ** slaDcs2c, slaDmxv, slaDcc2s, slaSubet, slaDranrm, slaDrange
|
|---|
| 24 | **
|
|---|
| 25 | ** Note:
|
|---|
| 26 | ** The equatorial coordinates are B1950.0 'FK4'. Use the
|
|---|
| 27 | ** routine slaEqgal if conversion from J2000.0 coordinates
|
|---|
| 28 | ** is required.
|
|---|
| 29 | **
|
|---|
| 30 | ** Reference:
|
|---|
| 31 | ** Blaauw et al, Mon.Not.R.astron.Soc.,121,123 (1960)
|
|---|
| 32 | **
|
|---|
| 33 | ** Last revision: 16 November 1993
|
|---|
| 34 | **
|
|---|
| 35 | ** Copyright P.T.Wallace. All rights reserved.
|
|---|
| 36 | */
|
|---|
| 37 | {
|
|---|
| 38 | double v1[3], v2[3], r, d;
|
|---|
| 39 |
|
|---|
| 40 | /*
|
|---|
| 41 | ** l2,b2 system of Galactic coordinates
|
|---|
| 42 | **
|
|---|
| 43 | ** p = 192.25 RA of Galactic north pole (mean B1950.0)
|
|---|
| 44 | ** q = 62.6 inclination of Galactic to mean B1950.0 equator
|
|---|
| 45 | ** r = 33 longitude of ascending node
|
|---|
| 46 | **
|
|---|
| 47 | ** p,q,r are degrees
|
|---|
| 48 | **
|
|---|
| 49 | ** Equatorial to Galactic rotation matrix
|
|---|
| 50 | **
|
|---|
| 51 | ** The Euler angles are p, q, 90-r, about the z then y then
|
|---|
| 52 | ** z axes.
|
|---|
| 53 | **
|
|---|
| 54 | ** +cp.cq.sr-sp.cr +sp.cq.sr+cp.cr -sq.sr
|
|---|
| 55 | **
|
|---|
| 56 | ** -cp.cq.cr-sp.sr -sp.cq.cr+cp.sr +sq.cr
|
|---|
| 57 | **
|
|---|
| 58 | ** +cp.sq +sp.sq +cq
|
|---|
| 59 | */
|
|---|
| 60 |
|
|---|
| 61 | static double rmat[3][3];
|
|---|
| 62 |
|
|---|
| 63 | rmat[0][0] = -0.066988739415;
|
|---|
| 64 | rmat[0][1] = -0.872755765852;
|
|---|
| 65 | rmat[0][2] = -0.483538914632;
|
|---|
| 66 | rmat[1][0] = 0.492728466075;
|
|---|
| 67 | rmat[1][1] = -0.450346958020;
|
|---|
| 68 | rmat[1][2] = 0.744584633283;
|
|---|
| 69 | rmat[2][0] = -0.867600811151;
|
|---|
| 70 | rmat[2][1] = -0.188374601723;
|
|---|
| 71 | rmat[2][2] = 0.460199784784;
|
|---|
| 72 |
|
|---|
| 73 |
|
|---|
| 74 | /* Remove e-terms */
|
|---|
| 75 | slaSubet ( dr, dd, 1950.0, &r, &d );
|
|---|
| 76 |
|
|---|
| 77 | /* Spherical to Cartesian */
|
|---|
| 78 | slaDcs2c ( r, d, v1 );
|
|---|
| 79 |
|
|---|
| 80 | /* Rotate to Galactic */
|
|---|
| 81 | slaDmxv ( rmat, v1, v2 );
|
|---|
| 82 |
|
|---|
| 83 | /* Cartesian to spherical */
|
|---|
| 84 | slaDcc2s ( v2, dl, db );
|
|---|
| 85 |
|
|---|
| 86 | /* Express angles in conventional ranges */
|
|---|
| 87 | *dl = slaDranrm ( *dl );
|
|---|
| 88 | *db = slaDrange ( *db );
|
|---|
| 89 | }
|
|---|
