/*
*+
* 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 sla_RVLSRD.
* 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 );
}