SUBROUTINE sla_EQGAL (DR, DD, DL, DB) *+ * - - - - - - * E Q G A L * - - - - - - * * Transformation from J2000.0 equatorial coordinates to * IAU 1958 galactic coordinates (double precision) * * Given: * DR,DD dp J2000.0 RA,Dec * * Returned: * DL,DB dp galactic longitude and latitude L2,B2 * * (all arguments are radians) * * Called: * sla_DCS2C, sla_DMXV, sla_DCC2S, sla_DRANRM, sla_DRANGE * * Note: * The equatorial coordinates are J2000.0. Use the routine * sla_EG50 if conversion from B1950.0 'FK4' coordinates is * required. * * Reference: * Blaauw et al, Mon.Not.R.Astron.Soc.,121,123 (1960) * * P.T.Wallace Starlink 21 September 1998 * * Copyright (C) 1998 Rutherford Appleton Laboratory *- IMPLICIT NONE DOUBLE PRECISION DR,DD,DL,DB DOUBLE PRECISION sla_DRANRM,sla_DRANGE DOUBLE PRECISION V1(3),V2(3) * * 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 (J2000.0), obtained by * applying the standard FK4 to FK5 transformation, for zero proper * motion in FK5, to the columns of the B1950 equatorial to * galactic rotation matrix: * 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)/ : -0.054875539726D0,-0.873437108010D0,-0.483834985808D0, : +0.494109453312D0,-0.444829589425D0,+0.746982251810D0, : -0.867666135858D0,-0.198076386122D0,+0.455983795705D0/ * Spherical to Cartesian CALL sla_DCS2C(DR,DD,V1) * Equatorial to galactic CALL sla_DMXV(RMAT,V1,V2) * Cartesian to spherical CALL sla_DCC2S(V2,DL,DB) * Express in conventional ranges DL=sla_DRANRM(DL) DB=sla_DRANGE(DB) END