REAL FUNCTION sla_RVLSRK (R2000, D2000) *+ * - - - - - - - * R V L S R K * - - - - - - - * * Velocity component in a given direction due to the Sun's motion * with respect to an adopted kinematic Local Standard of Rest. * * (single precision) * * Given: * R2000,D2000 r J2000.0 mean RA,Dec (radians) * * Result: * Component of "standard" solar motion in direction R2000,D2000 (km/s) * * Sign convention: * The result is +ve when the Sun is receding from the given point on * the sky. * * Note: The Local Standard of Rest used here is one of several * "kinematical" LSRs in common use. A kinematical LSR is the * mean standard of rest of specified star catalogues or stellar * populations. The Sun's motion with respect to a kinematical * LSR is known as the "standard" solar motion. * * There is another sort of LSR, the "dynamical" LSR, which is a * point in the vicinity of the Sun which is in a circular orbit * around the Galactic centre. The Sun's motion with respect to * the dynamical LSR is called the "peculiar" solar motion. To * obtain a radial velocity correction with respect to the * dynamical LSR use the routine sla_RVLSRD. * * Reference: Delhaye (1965), in "Stars and Stellar Systems", vol 5, * p73. * * Called: * sla_CS2C, sla_VDV * * P.T.Wallace Starlink 11 March 1994 * * 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 REAL R2000,D2000 REAL VA(3), VB(3) REAL sla_VDV * * Standard solar motion (from Methods of Experimental Physics, ed Meeks, * vol 12, part C, sec 6.1.5.2, p281): * * 20 km/s towards RA 18h Dec +30d (1900). * * The solar motion is expressed here in the form of a J2000.0 * equatorial Cartesian vector: * * VA(1) = X = -SPEED*COS(RA)*COS(DEC) * VA(2) = Y = -SPEED*SIN(RA)*COS(DEC) * VA(3) = Z = -SPEED*SIN(DEC) DATA VA / -0.29000, +17.31726, -10.00141 / * Convert given J2000 RA,Dec to x,y,z CALL sla_CS2C(R2000,D2000,VB) * Compute dot product with solar motion vector sla_RVLSRK=sla_VDV(VA,VB) END