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