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96 lines
3.0 KiB
Fortran
96 lines
3.0 KiB
Fortran
REAL FUNCTION sla_RVLSRD (R2000, D2000)
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*+
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* - - - - - - -
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* R V L S R D
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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 the dynamical 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 "peculiar" 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 the "dynamical" LSR,
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* a point in the vicinity of the Sun which is in a circular
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* orbit around the Galactic centre. The Sun's motion with
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* respect to the dynamical LSR is called the "peculiar" solar
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* motion.
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*
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* There is another type of LSR, called a "kinematical" LSR. A
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* kinematical LSR is the mean standard of rest of specified star
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* catalogues or stellar populations, and several slightly
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* different kinematical LSRs are in use. The Sun's motion with
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* respect to an agreed kinematical LSR is known as the "standard"
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* solar motion. To obtain a radial velocity correction with
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* respect to an adopted kinematical LSR use the routine sla_RVLSRK.
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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 9 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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* Peculiar solar motion from Delhaye 1965: in Galactic Cartesian
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* coordinates (+9,+12,+7) km/s. This corresponds to about 16.6 km/s
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* towards Galactic coordinates L2 = 53 deg, B2 = +25 deg, or RA,Dec
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* 17 49 58.7 +28 07 04 J2000.
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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 / +0.63823, +14.58542, -7.80116 /
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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_RVLSRD=sla_VDV(VA,VB)
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END
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