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95 lines
2.9 KiB
Fortran
95 lines
2.9 KiB
Fortran
REAL FUNCTION sla_RVLSRK (R2000, D2000)
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*+
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* - - - - - - -
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* R V L S R K
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* - - - - - - -
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*
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* Velocity component in a given direction due to the Sun's motion
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* with respect to an adopted kinematic Local Standard of Rest.
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*
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* (single precision)
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*
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* Given:
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* R2000,D2000 r J2000.0 mean RA,Dec (radians)
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*
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* Result:
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* Component of "standard" solar motion in direction R2000,D2000 (km/s)
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*
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* Sign convention:
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* The result is +ve when the Sun is receding from the given point on
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* the sky.
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*
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* Note: The Local Standard of Rest used here is one of several
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* "kinematical" LSRs in common use. A kinematical LSR is the
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* mean standard of rest of specified star catalogues or stellar
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* populations. The Sun's motion with respect to a kinematical
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* LSR is known as the "standard" solar motion.
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*
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* There is another sort of LSR, the "dynamical" LSR, which is a
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* point in the vicinity of the Sun which is in a circular orbit
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* around the Galactic centre. The Sun's motion with respect to
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* the dynamical LSR is called the "peculiar" solar motion. To
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* obtain a radial velocity correction with respect to the
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* dynamical LSR use the routine sla_RVLSRD.
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*
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* Reference: Delhaye (1965), in "Stars and Stellar Systems", vol 5,
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* p73.
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*
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* Called:
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* sla_CS2C, sla_VDV
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*
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* P.T.Wallace Starlink 11 March 1994
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*
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* Copyright (C) 1995 Rutherford Appleton Laboratory
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*
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* License:
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (see SLA_CONDITIONS); if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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*-
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IMPLICIT NONE
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REAL R2000,D2000
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REAL VA(3), VB(3)
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REAL sla_VDV
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*
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* Standard solar motion (from Methods of Experimental Physics, ed Meeks,
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* vol 12, part C, sec 6.1.5.2, p281):
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*
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* 20 km/s towards RA 18h Dec +30d (1900).
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*
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* The solar motion is expressed here in the form of a J2000.0
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* equatorial Cartesian vector:
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*
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* VA(1) = X = -SPEED*COS(RA)*COS(DEC)
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* VA(2) = Y = -SPEED*SIN(RA)*COS(DEC)
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* VA(3) = Z = -SPEED*SIN(DEC)
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DATA VA / -0.29000, +17.31726, -10.00141 /
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* Convert given J2000 RA,Dec to x,y,z
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CALL sla_CS2C(R2000,D2000,VB)
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* Compute dot product with solar motion vector
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sla_RVLSRK=sla_VDV(VA,VB)
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END
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