File Coverage

erfasrc/src/starpm.c
Criterion Covered Total %
statement 15 15 100.0
branch 2 4 50.0
condition n/a
subroutine n/a
pod n/a
total 17 19 89.4


line stmt bran cond sub pod time code
1             #include "erfa.h"
2              
3 1           int eraStarpm(double ra1, double dec1,
4             double pmr1, double pmd1, double px1, double rv1,
5             double ep1a, double ep1b, double ep2a, double ep2b,
6             double *ra2, double *dec2,
7             double *pmr2, double *pmd2, double *px2, double *rv2)
8             /*
9             ** - - - - - - - - - -
10             ** e r a S t a r p m
11             ** - - - - - - - - - -
12             **
13             ** Star proper motion: update star catalog data for space motion.
14             **
15             ** Given:
16             ** ra1 double right ascension (radians), before
17             ** dec1 double declination (radians), before
18             ** pmr1 double RA proper motion (radians/year), before
19             ** pmd1 double Dec proper motion (radians/year), before
20             ** px1 double parallax (arcseconds), before
21             ** rv1 double radial velocity (km/s, +ve = receding), before
22             ** ep1a double "before" epoch, part A (Note 1)
23             ** ep1b double "before" epoch, part B (Note 1)
24             ** ep2a double "after" epoch, part A (Note 1)
25             ** ep2b double "after" epoch, part B (Note 1)
26             **
27             ** Returned:
28             ** ra2 double right ascension (radians), after
29             ** dec2 double declination (radians), after
30             ** pmr2 double RA proper motion (radians/year), after
31             ** pmd2 double Dec proper motion (radians/year), after
32             ** px2 double parallax (arcseconds), after
33             ** rv2 double radial velocity (km/s, +ve = receding), after
34             **
35             ** Returned (function value):
36             ** int status:
37             ** -1 = system error (should not occur)
38             ** 0 = no warnings or errors
39             ** 1 = distance overridden (Note 6)
40             ** 2 = excessive velocity (Note 7)
41             ** 4 = solution didn't converge (Note 8)
42             ** else = binary logical OR of the above warnings
43             **
44             ** Notes:
45             **
46             ** 1) The starting and ending TDB dates ep1a+ep1b and ep2a+ep2b are
47             ** Julian Dates, apportioned in any convenient way between the two
48             ** parts (A and B). For example, JD(TDB)=2450123.7 could be
49             ** expressed in any of these ways, among others:
50             **
51             ** epna epnb
52             **
53             ** 2450123.7 0.0 (JD method)
54             ** 2451545.0 -1421.3 (J2000 method)
55             ** 2400000.5 50123.2 (MJD method)
56             ** 2450123.5 0.2 (date & time method)
57             **
58             ** The JD method is the most natural and convenient to use in
59             ** cases where the loss of several decimal digits of resolution
60             ** is acceptable. The J2000 method is best matched to the way
61             ** the argument is handled internally and will deliver the
62             ** optimum resolution. The MJD method and the date & time methods
63             ** are both good compromises between resolution and convenience.
64             **
65             ** 2) In accordance with normal star-catalog conventions, the object's
66             ** right ascension and declination are freed from the effects of
67             ** secular aberration. The frame, which is aligned to the catalog
68             ** equator and equinox, is Lorentzian and centered on the SSB.
69             **
70             ** The proper motions are the rate of change of the right ascension
71             ** and declination at the catalog epoch and are in radians per TDB
72             ** Julian year.
73             **
74             ** The parallax and radial velocity are in the same frame.
75             **
76             ** 3) Care is needed with units. The star coordinates are in radians
77             ** and the proper motions in radians per Julian year, but the
78             ** parallax is in arcseconds.
79             **
80             ** 4) The RA proper motion is in terms of coordinate angle, not true
81             ** angle. If the catalog uses arcseconds for both RA and Dec proper
82             ** motions, the RA proper motion will need to be divided by cos(Dec)
83             ** before use.
84             **
85             ** 5) Straight-line motion at constant speed, in the inertial frame,
86             ** is assumed.
87             **
88             ** 6) An extremely small (or zero or negative) parallax is interpreted
89             ** to mean that the object is on the "celestial sphere", the radius
90             ** of which is an arbitrary (large) value (see the eraStarpv
91             ** function for the value used). When the distance is overridden in
92             ** this way, the status, initially zero, has 1 added to it.
93             **
94             ** 7) If the space velocity is a significant fraction of c (see the
95             ** constant VMAX in the function eraStarpv), it is arbitrarily set
96             ** to zero. When this action occurs, 2 is added to the status.
97             **
98             ** 8) The relativistic adjustment carried out in the eraStarpv function
99             ** involves an iterative calculation. If the process fails to
100             ** converge within a set number of iterations, 4 is added to the
101             ** status.
102             **
103             ** Called:
104             ** eraStarpv star catalog data to space motion pv-vector
105             ** eraPvu update a pv-vector
106             ** eraPdp scalar product of two p-vectors
107             ** eraPvstar space motion pv-vector to star catalog data
108             **
109             ** Copyright (C) 2013-2020, NumFOCUS Foundation.
110             ** Derived, with permission, from the SOFA library. See notes at end of file.
111             */
112             {
113             double pv1[2][3], tl1, dt, pv[2][3], r2, rdv, v2, c2mv2, tl2,
114             pv2[2][3];
115             int j1, j2, j;
116              
117              
118             /* RA,Dec etc. at the "before" epoch to space motion pv-vector. */
119 1           j1 = eraStarpv(ra1, dec1, pmr1, pmd1, px1, rv1, pv1);
120              
121             /* Light time when observed (days). */
122 1           tl1 = eraPm(pv1[0]) / ERFA_DC;
123              
124             /* Time interval, "before" to "after" (days). */
125 1           dt = (ep2a - ep1a) + (ep2b - ep1b);
126              
127             /* Move star along track from the "before" observed position to the */
128             /* "after" geometric position. */
129 1           eraPvu(dt + tl1, pv1, pv);
130              
131             /* From this geometric position, deduce the observed light time (days) */
132             /* at the "after" epoch (with theoretically unneccessary error check). */
133 1           r2 = eraPdp(pv[0], pv[0]);
134 1           rdv = eraPdp(pv[0], pv[1]);
135 1           v2 = eraPdp(pv[1], pv[1]);
136 1           c2mv2 = ERFA_DC*ERFA_DC - v2;
137 1 50         if (c2mv2 <= 0) return -1;
138 1           tl2 = (-rdv + sqrt(rdv*rdv + c2mv2*r2)) / c2mv2;
139              
140             /* Move the position along track from the observed place at the */
141             /* "before" epoch to the observed place at the "after" epoch. */
142 1           eraPvu(dt + (tl1 - tl2), pv1, pv2);
143              
144             /* Space motion pv-vector to RA,Dec etc. at the "after" epoch. */
145 1           j2 = eraPvstar(pv2, ra2, dec2, pmr2, pmd2, px2, rv2);
146              
147             /* Final status. */
148 1 50         j = (j2 == 0) ? j1 : -1;
149              
150 1           return j;
151              
152             }
153             /*----------------------------------------------------------------------
154             **
155             **
156             ** Copyright (C) 2013-2020, NumFOCUS Foundation.
157             ** All rights reserved.
158             **
159             ** This library is derived, with permission, from the International
160             ** Astronomical Union's "Standards of Fundamental Astronomy" library,
161             ** available from http://www.iausofa.org.
162             **
163             ** The ERFA version is intended to retain identical functionality to
164             ** the SOFA library, but made distinct through different function and
165             ** file names, as set out in the SOFA license conditions. The SOFA
166             ** original has a role as a reference standard for the IAU and IERS,
167             ** and consequently redistribution is permitted only in its unaltered
168             ** state. The ERFA version is not subject to this restriction and
169             ** therefore can be included in distributions which do not support the
170             ** concept of "read only" software.
171             **
172             ** Although the intent is to replicate the SOFA API (other than
173             ** replacement of prefix names) and results (with the exception of
174             ** bugs; any that are discovered will be fixed), SOFA is not
175             ** responsible for any errors found in this version of the library.
176             **
177             ** If you wish to acknowledge the SOFA heritage, please acknowledge
178             ** that you are using a library derived from SOFA, rather than SOFA
179             ** itself.
180             **
181             **
182             ** TERMS AND CONDITIONS
183             **
184             ** Redistribution and use in source and binary forms, with or without
185             ** modification, are permitted provided that the following conditions
186             ** are met:
187             **
188             ** 1 Redistributions of source code must retain the above copyright
189             ** notice, this list of conditions and the following disclaimer.
190             **
191             ** 2 Redistributions in binary form must reproduce the above copyright
192             ** notice, this list of conditions and the following disclaimer in
193             ** the documentation and/or other materials provided with the
194             ** distribution.
195             **
196             ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
197             ** the International Astronomical Union nor the names of its
198             ** contributors may be used to endorse or promote products derived
199             ** from this software without specific prior written permission.
200             **
201             ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
202             ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
203             ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
204             ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
205             ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
206             ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
207             ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
208             ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
209             ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
210             ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
211             ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
212             ** POSSIBILITY OF SUCH DAMAGE.
213             **
214             */