SUBROUTINE slEQEC (DR, DD, DATE, DL, DB) *+ * - - - - - - * E Q E C * - - - - - - * * Transformation from J2000.0 equatorial coordinates to * ecliptic coordinates (double precision) * * Given: * DR,DD dp J2000.0 mean RA,Dec (radians) * DATE dp TDB (loosely ET) as Modified Julian Date * (JD-2400000.5) * Returned: * DL,DB dp ecliptic longitude and latitude * (mean of date, IAU 1980 theory, radians) * * Called: * slDS2C, slPREC, slEPJ, slDMXV, slECMA, slDC2S, * slDA2P, slDA1P * * P.T.Wallace Starlink March 1986 * * 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., 51 Franklin Street, Fifth Floor, * Boston, MA 02110-1301 USA * * Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. *- IMPLICIT NONE DOUBLE PRECISION DR,DD,DATE,DL,DB DOUBLE PRECISION slEPJ,slDA2P,slDA1P DOUBLE PRECISION RMAT(3,3),V1(3),V2(3) * Spherical to Cartesian CALL slDS2C(DR,DD,V1) * Mean J2000 to mean of date CALL slPREC(2000D0,slEPJ(DATE),RMAT) CALL slDMXV(RMAT,V1,V2) * Equatorial to ecliptic CALL slECMA(DATE,RMAT) CALL slDMXV(RMAT,V2,V1) * Cartesian to spherical CALL slDC2S(V1,DL,DB) * Express in conventional ranges DL=slDA2P(DL) DB=slDA1P(DB) END