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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
*-
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
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