FACT++  1.0
utcut1.c
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1 #include "erfa.h"
2 
3 int eraUtcut1(double utc1, double utc2, double dut1,
4  double *ut11, double *ut12)
5 /*
6 ** - - - - - - - - - -
7 ** e r a U t c u t 1
8 ** - - - - - - - - - -
9 **
10 ** Time scale transformation: Coordinated Universal Time, UTC, to
11 ** Universal Time, UT1.
12 **
13 ** Given:
14 ** utc1,utc2 double UTC as a 2-part quasi Julian Date (Notes 1-4)
15 ** dut1 double Delta UT1 = UT1-UTC in seconds (Note 5)
16 **
17 ** Returned:
18 ** ut11,ut12 double UT1 as a 2-part Julian Date (Note 6)
19 **
20 ** Returned (function value):
21 ** int status: +1 = dubious year (Note 3)
22 ** 0 = OK
23 ** -1 = unacceptable date
24 **
25 ** Notes:
26 **
27 ** 1) utc1+utc2 is quasi Julian Date (see Note 2), apportioned in any
28 ** convenient way between the two arguments, for example where utc1
29 ** is the Julian Day Number and utc2 is the fraction of a day.
30 **
31 ** 2) JD cannot unambiguously represent UTC during a leap second unless
32 ** special measures are taken. The convention in the present
33 ** function is that the JD day represents UTC days whether the
34 ** length is 86399, 86400 or 86401 SI seconds.
35 **
36 ** 3) The warning status "dubious year" flags UTCs that predate the
37 ** introduction of the time scale or that are too far in the future
38 ** to be trusted. See eraDat for further details.
39 **
40 ** 4) The function eraDtf2d converts from calendar date and time of
41 ** day into 2-part Julian Date, and in the case of UTC implements
42 ** the leap-second-ambiguity convention described above.
43 **
44 ** 5) Delta UT1 can be obtained from tabulations provided by the
45 ** International Earth Rotation and Reference Systems Service.
46 ** It is the caller's responsibility to supply a dut1 argument
47 ** containing the UT1-UTC value that matches the given UTC.
48 **
49 ** 6) The returned ut11,ut12 are such that their sum is the UT1 Julian
50 ** Date.
51 **
52 ** References:
53 **
54 ** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
55 ** IERS Technical Note No. 32, BKG (2004)
56 **
57 ** Explanatory Supplement to the Astronomical Almanac,
58 ** P. Kenneth Seidelmann (ed), University Science Books (1992)
59 **
60 ** Called:
61 ** eraJd2cal JD to Gregorian calendar
62 ** eraDat delta(AT) = TAI-UTC
63 ** eraUtctai UTC to TAI
64 ** eraTaiut1 TAI to UT1
65 **
66 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
67 ** Derived, with permission, from the SOFA library. See notes at end of file.
68 */
69 {
70  int iy, im, id, js, jw;
71  double w, dat, dta, tai1, tai2;
72 
73 /* Look up TAI-UTC. */
74  if ( eraJd2cal(utc1, utc2, &iy, &im, &id, &w) ) return -1;
75  js = eraDat ( iy, im, id, 0.0, &dat);
76  if ( js < 0 ) return -1;
77 
78 /* Form UT1-TAI. */
79  dta = dut1 - dat;
80 
81 /* UTC to TAI to UT1. */
82  jw = eraUtctai(utc1, utc2, &tai1, &tai2);
83  if ( jw < 0 ) {
84  return -1;
85  } else if ( jw > 0 ) {
86  js = jw;
87  }
88  if ( eraTaiut1(tai1, tai2, dta, ut11, ut12) ) return -1;
89 
90 /* Status. */
91  return js;
92 
93 }
94 /*----------------------------------------------------------------------
95 **
96 **
97 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
98 ** All rights reserved.
99 **
100 ** This library is derived, with permission, from the International
101 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
102 ** available from http://www.iausofa.org.
103 **
104 ** The ERFA version is intended to retain identical functionality to
105 ** the SOFA library, but made distinct through different function and
106 ** file names, as set out in the SOFA license conditions. The SOFA
107 ** original has a role as a reference standard for the IAU and IERS,
108 ** and consequently redistribution is permitted only in its unaltered
109 ** state. The ERFA version is not subject to this restriction and
110 ** therefore can be included in distributions which do not support the
111 ** concept of "read only" software.
112 **
113 ** Although the intent is to replicate the SOFA API (other than
114 ** replacement of prefix names) and results (with the exception of
115 ** bugs; any that are discovered will be fixed), SOFA is not
116 ** responsible for any errors found in this version of the library.
117 **
118 ** If you wish to acknowledge the SOFA heritage, please acknowledge
119 ** that you are using a library derived from SOFA, rather than SOFA
120 ** itself.
121 **
122 **
123 ** TERMS AND CONDITIONS
124 **
125 ** Redistribution and use in source and binary forms, with or without
126 ** modification, are permitted provided that the following conditions
127 ** are met:
128 **
129 ** 1 Redistributions of source code must retain the above copyright
130 ** notice, this list of conditions and the following disclaimer.
131 **
132 ** 2 Redistributions in binary form must reproduce the above copyright
133 ** notice, this list of conditions and the following disclaimer in
134 ** the documentation and/or other materials provided with the
135 ** distribution.
136 **
137 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
138 ** the International Astronomical Union nor the names of its
139 ** contributors may be used to endorse or promote products derived
140 ** from this software without specific prior written permission.
141 **
142 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
143 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
144 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
145 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
146 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
147 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
148 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
149 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
150 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
151 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
152 ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
153 ** POSSIBILITY OF SUCH DAMAGE.
154 **
155 */
int eraTaiut1(double tai1, double tai2, double dta, double *ut11, double *ut12)
Definition: taiut1.c:3
int eraUtctai(double utc1, double utc2, double *tai1, double *tai2)
Definition: utctai.c:3
char id[4]
Definition: FITS.h:71
int eraJd2cal(double dj1, double dj2, int *iy, int *im, int *id, double *fd)
Definition: jd2cal.c:3
int eraDat(int iy, int im, int id, double fd, double *deltat)
Definition: dat.c:3
int eraUtcut1(double utc1, double utc2, double dut1, double *ut11, double *ut12)
Definition: utcut1.c:3