FACT++  1.0
palRvlsrk.c
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1 /*
2 *+
3 * Name:
4 * palRvlsrk
5 
6 * Purpose:
7 * Velocity component in a given direction due to the Sun's motion
8 * with respect to an adopted kinematic Local Standard of Rest.
9 
10 * Language:
11 * Starlink ANSI C
12 
13 * Type of Module:
14 * Library routine
15 
16 * Invocation:
17 * double palRvlsrk( double r2000, double d2000 )
18 
19 * Arguments:
20 * r2000 = double (Given)
21 * J2000.0 mean RA (radians)
22 * d2000 = double (Given)
23 * J2000.0 mean Dec (radians)
24 
25 * Returned Value:
26 * Component of "standard" solar motion in direction R2000,D2000 (km/s).
27 
28 * Description:
29 * This function returns the velocity component in a given direction
30 * due to the Sun's motion with respect to an adopted kinematic
31 * Local Standard of Rest. The result is +ve when the Sun is receding
32 * from the given point on the sky.
33 
34 * Notes:
35 * - The Local Standard of Rest used here is one of several
36 * "kinematical" LSRs in common use. A kinematical LSR is the mean
37 * standard of rest of specified star catalogues or stellar
38 * populations. The Sun's motion with respect to a kinematical LSR
39 * is known as the "standard" solar motion.
40 * - There is another sort of LSR, the "dynamical" LSR, which is a
41 * point in the vicinity of the Sun which is in a circular orbit
42 * around the Galactic centre. The Sun's motion with respect to
43 * the dynamical LSR is called the "peculiar" solar motion. To
44 * obtain a radial velocity correction with respect to the
45 * dynamical LSR use the routine palRvlsrd.
46 
47 * Reference:
48 * - Delhaye (1965), in "Stars and Stellar Systems", vol 5, p73.
49 
50 * Authors:
51 * PTW: Pat Wallace (STFC)
52 * DSB: David Berry (JAC, Hawaii)
53 * {enter_new_authors_here}
54 
55 * History:
56 * 2012-02-16 (DSB):
57 * Initial version.
58 * Adapted with permission from the Fortran SLALIB library.
59 * {enter_further_changes_here}
60 
61 * Copyright:
62 * Copyright (C) 1995 Rutherford Appleton Laboratory
63 * Copyright (C) 2012 Science and Technology Facilities Council.
64 * All Rights Reserved.
65 
66 * Licence:
67 * This program is free software: you can redistribute it and/or
68 * modify it under the terms of the GNU Lesser General Public
69 * License as published by the Free Software Foundation, either
70 * version 3 of the License, or (at your option) any later
71 * version.
72 *
73 * This program is distributed in the hope that it will be useful,
74 * but WITHOUT ANY WARRANTY; without even the implied warranty of
75 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
76 * GNU Lesser General Public License for more details.
77 *
78 * You should have received a copy of the GNU Lesser General
79 * License along with this program. If not, see
80 * <http://www.gnu.org/licenses/>.
81 
82 * Bugs:
83 * {note_any_bugs_here}
84 *-
85 */
86 
87 #include "pal.h"
88 #include "pal1sofa.h"
89 
90 double palRvlsrk( double r2000, double d2000 ){
91 
92 /* Local Variables: */
93  double vb[ 3 ];
94 
95 /*
96 * Standard solar motion (from Methods of Experimental Physics, ed Meeks,
97 * vol 12, part C, sec 6.1.5.2, p281):
98 *
99 * 20 km/s towards RA 18h Dec +30d (1900).
100 *
101 * The solar motion is expressed here in the form of a J2000.0
102 * equatorial Cartesian vector:
103 *
104 * VA(1) = X = -SPEED*COS(RA)*COS(DEC)
105 * VA(2) = Y = -SPEED*SIN(RA)*COS(DEC)
106 * VA(3) = Z = -SPEED*SIN(DEC)
107 */
108 
109  double va[ 3 ] = { -0.29000, +17.31726, -10.00141 };
110 
111 /* Convert given J2000 RA,Dec to x,y,z. */
112  eraS2c( r2000, d2000, vb );
113 
114 /* Compute dot product with Solar motion vector. */
115  return eraPdp( va, vb );
116 }
double eraPdp(double a[3], double b[3])
Definition: pdp.c:3
void eraS2c(double theta, double phi, double c[3])
Definition: s2c.c:3
double palRvlsrk(double r2000, double d2000)
Definition: palRvlsrk.c:90