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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
*-
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
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