File: palRvlsrk.c

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 `123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116` ``````/* *+ * Name: * palRvlsrk * Purpose: * Velocity component in a given direction due to the Sun's motion * with respect to an adopted kinematic Local Standard of Rest. * Language: * Starlink ANSI C * Type of Module: * Library routine * Invocation: * double palRvlsrk( double r2000, double d2000 ) * Arguments: * r2000 = double (Given) * J2000.0 mean RA (radians) * d2000 = double (Given) * J2000.0 mean Dec (radians) * Returned Value: * Component of "standard" solar motion in direction R2000,D2000 (km/s). * Description: * This function returns the velocity component in a given direction * due to the Sun's motion with respect to an adopted kinematic * Local Standard of Rest. The result is +ve when the Sun is receding * from the given point on the sky. * Notes: * - 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 palRvlsrd. * Reference: * - Delhaye (1965), in "Stars and Stellar Systems", vol 5, p73. * Authors: * PTW: Pat Wallace (STFC) * DSB: David Berry (JAC, Hawaii) * {enter_new_authors_here} * History: * 2012-02-16 (DSB): * Initial version. * Adapted with permission from the Fortran SLALIB library. * {enter_further_changes_here} * Copyright: * Copyright (C) 1995 Rutherford Appleton Laboratory * Copyright (C) 2012 Science and Technology Facilities Council. * All Rights Reserved. * Licence: * This program is free software: you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation, either * version 3 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 Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General * License along with this program. If not, see * . * Bugs: * {note_any_bugs_here} *- */ #include "pal.h" #include "pal1sofa.h" double palRvlsrk( double r2000, double d2000 ){ /* Local Variables: */ double vb[ 3 ]; /* * 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) */ double va[ 3 ] = { -0.29000, +17.31726, -10.00141 }; /* Convert given J2000 RA,Dec to x,y,z. */ eraS2c( r2000, d2000, vb ); /* Compute dot product with Solar motion vector. */ return eraPdp( va, vb ); } ``````