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82 lines
2.1 KiB
Fortran
82 lines
2.1 KiB
Fortran
REAL FUNCTION sla_RVLG (R2000, D2000)
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*+
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* - - - - -
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* R V L G
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* - - - - -
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*
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* Velocity component in a given direction due to the combination
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* of the rotation of the Galaxy and the motion of the Galaxy
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* relative to the mean motion of the local group (single precision)
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*
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* Given:
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* R2000,D2000 real J2000.0 mean RA,Dec (radians)
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*
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* Result:
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* Component of 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
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* given point on the sky.
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*
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* Reference:
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* IAU Trans 1976, 168, p201.
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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 June 1985
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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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* Solar velocity due to Galactic rotation and translation
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*
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* Speed = 300 km/s
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*
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* Apex = L2,B2 90deg, 0deg
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* = RA,Dec 21 12 01.1 +48 19 47 J2000.0
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*
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* This is expressed in the form of a J2000.0 x,y,z 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 / -148.23284, +133.44888, -224.09467 /
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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_RVLG=sla_VDV(VA,VB)
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END
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