SUBROUTINE sla_GE50 (DL, DB, DR, DD) *+ * - - - - - * G E 5 0 * - - - - - * * Transformation from IAU 1958 galactic coordinates to * B1950.0 'FK4' equatorial coordinates (double precision) * * Given: * DL,DB dp galactic longitude and latitude L2,B2 * * Returned: * DR,DD dp B1950.0 'FK4' RA,Dec * * (all arguments are radians) * * Called: * sla_DCS2C, sla_DIMXV, sla_DCC2S, sla_ADDET, sla_DRANRM, sla_DRANGE * * Note: * The equatorial coordinates are B1950.0 'FK4'. Use the * routine sla_GALEQ if conversion to J2000.0 coordinates * is required. * * Reference: * Blaauw et al, Mon.Not.R.Astron.Soc.,121,123 (1960) * * P.T.Wallace Starlink 5 September 1993 * * Copyright (C) 1995 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 DL,DB,DR,DD DOUBLE PRECISION sla_DRANRM,sla_DRANGE DOUBLE PRECISION V1(3),V2(3),R,D,RE,DE * * L2,B2 system of galactic coordinates * * P = 192.25 RA of galactic north pole (mean B1950.0) * Q = 62.6 inclination of galactic to mean B1950.0 equator * R = 33 longitude of ascending node * * P,Q,R are degrees * * * Equatorial to galactic rotation matrix * * The Euler angles are P, Q, 90-R, about the z then y then * z axes. * * +CP.CQ.SR-SP.CR +SP.CQ.SR+CP.CR -SQ.SR * * -CP.CQ.CR-SP.SR -SP.CQ.CR+CP.SR +SQ.CR * * +CP.SQ +SP.SQ +CQ * DOUBLE PRECISION RMAT(3,3) DATA RMAT(1,1),RMAT(1,2),RMAT(1,3), : RMAT(2,1),RMAT(2,2),RMAT(2,3), : RMAT(3,1),RMAT(3,2),RMAT(3,3) / : -0.066988739415D0,-0.872755765852D0,-0.483538914632D0, : +0.492728466075D0,-0.450346958020D0,+0.744584633283D0, : -0.867600811151D0,-0.188374601723D0,+0.460199784784D0 / * Spherical to Cartesian CALL sla_DCS2C(DL,DB,V1) * Rotate to mean B1950.0 CALL sla_DIMXV(RMAT,V1,V2) * Cartesian to spherical CALL sla_DCC2S(V2,R,D) * Introduce E-terms CALL sla_ADDET(R,D,1950D0,RE,DE) * Express in conventional ranges DR=sla_DRANRM(RE) DD=sla_DRANGE(DE) END