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slalib/rvlsrd.f

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+      REAL FUNCTION sla_RVLSRD (R2000, D2000)
+*+
+*     - - - - - - -
+*      R V L S R D
+*     - - - - - - -
+*
+*  Velocity component in a given direction due to the Sun's motion
+*  with respect to the dynamical Local Standard of Rest.
+*
+*  (single precision)
+*
+*  Given:
+*     R2000,D2000   r    J2000.0 mean RA,Dec (radians)
+*
+*  Result:
+*     Component of "peculiar" 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 the "dynamical" LSR,
+*         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.
+*
+*         There is another type of LSR, called a "kinematical" LSR.  A
+*         kinematical LSR is the mean standard of rest of specified star
+*         catalogues or stellar populations, and several slightly
+*         different kinematical LSRs are in use.  The Sun's motion with
+*         respect to an agreed kinematical LSR is known as the "standard"
+*         solar motion.  To obtain a radial velocity correction with
+*         respect to an adopted kinematical LSR use the routine sla_RVLSRK.
+*
+*  Reference:  Delhaye (1965), in "Stars and Stellar Systems", vol 5,
+*              p73.
+*
+*  Called:
+*     sla_CS2C, sla_VDV
+*
+*  P.T.Wallace   Starlink   9 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
+
+*
+*  Peculiar solar motion from Delhaye 1965: in Galactic Cartesian
+*  coordinates (+9,+12,+7) km/s.  This corresponds to about 16.6 km/s
+*  towards Galactic coordinates L2 = 53 deg, B2 = +25 deg, or RA,Dec
+*  17 49 58.7 +28 07 04 J2000.
+*
+*  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 / +0.63823, +14.58542, -7.80116 /
+
+
+
+*  Convert given J2000 RA,Dec to x,y,z
+      CALL sla_CS2C(R2000,D2000,VB)
+
+*  Compute dot product with solar motion vector
+      sla_RVLSRD=sla_VDV(VA,VB)
+
+      END