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REAL FUNCTION sla_RVLG (R2000, D2000)
*+
* - - - - -
* R V L G
* - - - - -
*
* Velocity component in a given direction due to the combination
* of the rotation of the Galaxy and the motion of the Galaxy
* relative to the mean motion of the local group (single precision)
*
* Given:
* R2000,D2000 real J2000.0 mean RA,Dec (radians)
*
* Result:
* Component of 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.
*
* Reference:
* IAU Trans 1976, 168, p201.
*
* Called:
* sla_CS2C, sla_VDV
*
* P.T.Wallace Starlink June 1985
*
* Copyright (C) 1995 Rutherford Appleton Laboratory
*-
IMPLICIT NONE
REAL R2000,D2000
REAL VA(3), VB(3)
REAL sla_VDV
*
* Solar velocity due to Galactic rotation and translation
*
* Speed = 300 km/s
*
* Apex = L2,B2 90deg, 0deg
* = RA,Dec 21 12 01.1 +48 19 47 J2000.0
*
* This is expressed in the form of a J2000.0 x,y,z 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 / -148.23284, +133.44888, -224.09467 /
* Convert given J2000 RA,Dec to x,y,z
CALL sla_CS2C(R2000,D2000,VB)
* Compute dot product with Solar motion vector
sla_RVLG=sla_VDV(VA,VB)
END
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