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palRvgalc.c
Go to the documentation of this file.
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/*
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*+
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* Name:
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* palRvgalc
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* Purpose:
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* Velocity component in a given direction due to the rotation
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* of the Galaxy.
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* Language:
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* Starlink ANSI C
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* Type of Module:
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* Library routine
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* Invocation:
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* double palRvgalc( double r2000, double d2000 )
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* Arguments:
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* r2000 = double (Given)
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* J2000.0 mean RA (radians)
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* d2000 = double (Given)
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* J2000.0 mean Dec (radians)
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* Returned Value:
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* Component of dynamical LSR motion in direction R2000,D2000 (km/s).
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* Description:
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* This function returns the Component of dynamical LSR motion in
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* the direction of R2000,D2000. The result is +ve when the dynamical
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* LSR is receding from the given point on the sky.
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*
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* Notes:
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* - The Local Standard of Rest used here is a point in the
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* vicinity of the Sun which is in a circular orbit around
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* the Galactic centre. Sometimes called the "dynamical" LSR,
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* it is not to be confused with a "kinematical" LSR, which
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* is the mean standard of rest of star catalogues or stellar
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* populations.
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*
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* Reference:
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* - The orbital speed of 220 km/s used here comes from Kerr &
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* Lynden-Bell (1986), MNRAS, 221, p1023.
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* Authors:
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* PTW: Pat Wallace (STFC)
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* DSB: David Berry (JAC, Hawaii)
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* {enter_new_authors_here}
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* History:
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* 2012-02-16 (DSB):
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* Initial version.
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* Adapted with permission from the Fortran SLALIB library.
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* {enter_further_changes_here}
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* Copyright:
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* Copyright (C) 1995 Rutherford Appleton Laboratory
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* Copyright (C) 2012 Science and Technology Facilities Council.
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* All Rights Reserved.
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* Licence:
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* This program is free software: you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation, either
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* version 3 of the License, or (at your option) any later
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* 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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General
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* License along with this program. If not, see
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* <http://www.gnu.org/licenses/>.
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* Bugs:
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* {note_any_bugs_here}
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*-
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*/
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#include "
pal.h
"
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#include "
pal1sofa.h
"
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double
palRvgalc
(
double
r2000,
double
d2000 ){
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/* Local Variables: */
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double
vb[ 3 ];
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/*
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* LSR velocity due to Galactic rotation
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*
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* Speed = 220 km/s
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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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*/
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double
va[ 3 ] = { -108.70408, +97.86251, -164.33610 };
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/* Convert given J2000 RA,Dec to x,y,z. */
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eraS2c
( r2000, d2000, vb );
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/* Compute dot product with LSR motion vector. */
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return
eraPdp
( va, vb );
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}
eraPdp
double eraPdp(double a[3], double b[3])
Definition:
pdp.c:3
pal.h
palRvgalc
double palRvgalc(double r2000, double d2000)
Definition:
palRvgalc.c:85
eraS2c
void eraS2c(double theta, double phi, double c[3])
Definition:
s2c.c:3
pal1sofa.h
pal
palRvgalc.c
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