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author | William Joye <wjoye@cfa.harvard.edu> | 2018-09-21 17:04:03 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2018-09-21 17:04:03 (GMT) |
commit | 28518ab5eb4726fe91ee0c916b2322f8c47eb3ad (patch) | |
tree | 2653f0ce7e9c70973f27fe6c0c38ec31e21ce5cf /ast/pal/palRvgalc.c | |
parent | bd7d67f66c53df36bb50e3423bfc91eae8618201 (diff) | |
download | blt-28518ab5eb4726fe91ee0c916b2322f8c47eb3ad.zip blt-28518ab5eb4726fe91ee0c916b2322f8c47eb3ad.tar.gz blt-28518ab5eb4726fe91ee0c916b2322f8c47eb3ad.tar.bz2 |
update ast 8.6.3
Diffstat (limited to 'ast/pal/palRvgalc.c')
-rw-r--r-- | ast/pal/palRvgalc.c | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/ast/pal/palRvgalc.c b/ast/pal/palRvgalc.c new file mode 100644 index 0000000..2f01576 --- /dev/null +++ b/ast/pal/palRvgalc.c @@ -0,0 +1,111 @@ +/* +*+ +* Name: +* palRvgalc + +* Purpose: +* Velocity component in a given direction due to the rotation +* of the Galaxy. + +* Language: +* Starlink ANSI C + +* Type of Module: +* Library routine + +* Invocation: +* double palRvgalc( double r2000, double d2000 ) + +* Arguments: +* r2000 = double (Given) +* J2000.0 mean RA (radians) +* d2000 = double (Given) +* J2000.0 mean Dec (radians) + +* Returned Value: +* Component of dynamical LSR motion in direction R2000,D2000 (km/s). + +* Description: +* This function returns the Component of dynamical LSR motion in +* the direction of R2000,D2000. The result is +ve when the dynamical +* LSR is receding from the given point on the sky. +* +* Notes: +* - The Local Standard of Rest used here is a point in the +* vicinity of the Sun which is in a circular orbit around +* the Galactic centre. Sometimes called the "dynamical" LSR, +* it is not to be confused with a "kinematical" LSR, which +* is the mean standard of rest of star catalogues or stellar +* populations. +* +* Reference: +* - The orbital speed of 220 km/s used here comes from Kerr & +* Lynden-Bell (1986), MNRAS, 221, p1023. + +* Authors: +* PTW: Pat Wallace (STFC) +* DSB: David Berry (JAC, Hawaii) +* {enter_new_authors_here} + +* History: +* 2012-02-16 (DSB): +* Initial version. +* Adapted with permission from the Fortran SLALIB library. +* {enter_further_changes_here} + +* Copyright: +* Copyright (C) 1995 Rutherford Appleton Laboratory +* Copyright (C) 2012 Science and Technology Facilities Council. +* All Rights Reserved. + +* Licence: +* This program is free software: you can redistribute it and/or +* modify it under the terms of the GNU Lesser General Public +* License as published by the Free Software Foundation, either +* version 3 of the License, or (at your option) any later +* version. +* +* This program is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +* GNU Lesser General Public License for more details. +* +* You should have received a copy of the GNU Lesser General +* License along with this program. If not, see +* <http://www.gnu.org/licenses/>. + +* Bugs: +* {note_any_bugs_here} +*- +*/ + +#include "pal.h" +#include "pal1sofa.h" + +double palRvgalc( double r2000, double d2000 ){ + +/* Local Variables: */ + double vb[ 3 ]; + +/* +* LSR velocity due to Galactic rotation +* +* Speed = 220 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) +*/ + + double va[ 3 ] = { -108.70408, +97.86251, -164.33610 }; + +/* Convert given J2000 RA,Dec to x,y,z. */ + eraS2c( r2000, d2000, vb ); + +/* Compute dot product with LSR motion vector. */ + return eraPdp( va, vb ); +} |