File Coverage

palsrc/palRverot.c
Criterion Covered Total %
statement 0 2 0.0
branch n/a
condition n/a
subroutine n/a
pod n/a
total 0 2 0.0


line stmt bran cond sub pod time code
1             /*
2             *+
3             * Name:
4             * palRverot
5              
6             * Purpose:
7             * Velocity component in a given direction due to Earth rotation
8              
9             * Language:
10             * Starlink ANSI C
11              
12             * Type of Module:
13             * Library routine
14              
15             * Invocation:
16             * double palRverot ( double phi, double ra, double da, double st );
17              
18             * Arguments:
19             * phi = double (Given)
20             * latitude of observing station (geodetic) (radians)
21             * ra = double (Given)
22             * apparent RA (radians)
23             * da = double (Given)
24             * apparent Dec (radians)
25             * st = double (Given)
26             * Local apparent sidereal time.
27              
28             * Returned Value:
29             * palRverot = double
30             * Component of Earth rotation in direction RA,DA (km/s).
31             * The result is +ve when the observatory is receding from the
32             * given point on the sky.
33              
34             * Description:
35             * Calculate the velocity component in a given direction due to Earth
36             * rotation.
37             *
38             * The simple algorithm used assumes a spherical Earth, of
39             * a radius chosen to give results accurate to about 0.0005 km/s
40             * for observing stations at typical latitudes and heights. For
41             * applications requiring greater precision, use the routine
42             * palPvobs.
43              
44             * Authors:
45             * PTW: Patrick T. Wallace
46             * TIMJ: Tim Jenness (JAC, Hawaii)
47             * {enter_new_authors_here}
48              
49             * History:
50             * 2012-03-02 (TIMJ):
51             * Initial version
52             * Adapted with permission from the Fortran SLALIB library.
53             * {enter_further_changes_here}
54              
55             * Copyright:
56             * Copyright (C) 1995 Rutherford Appleton Laboratory
57             * Copyright (C) 2012 Science and Technology Facilities Council.
58             * All Rights Reserved.
59              
60             * Licence:
61             * This program is free software; you can redistribute it and/or
62             * modify it under the terms of the GNU General Public License as
63             * published by the Free Software Foundation; either version 3 of
64             * the License, or (at your option) any later version.
65             *
66             * This program is distributed in the hope that it will be
67             * useful, but WITHOUT ANY WARRANTY; without even the implied
68             * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
69             * PURPOSE. See the GNU General Public License for more details.
70             *
71             * You should have received a copy of the GNU General Public License
72             * along with this program; if not, write to the Free Software
73             * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
74             * MA 02110-1301, USA.
75              
76             * Bugs:
77             * {note_any_bugs_here}
78             *-
79             */
80              
81             #include "pal.h"
82              
83             #include
84              
85 0           double palRverot ( double phi, double ra, double da, double st ) {
86              
87             /* Nominal mean sidereal speed of Earth equator in km/s (the actual
88             * value is about 0.4651) */
89             const double espeed = 0.4655;
90 0           return espeed * cos(phi) * sin(st-ra) * cos(da);
91             }