1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
use ;
/// Transform star RA,Dec from geocentric CIRS to ICRS astrometric.
///
/// This function is part of the International Astronomical Union's
/// SOFA (Standards of Fundamental Astronomy) software collection.
///
/// Status: support function.
///
/// Given:
/// ```
/// ri,di double CIRS geocentric RA,Dec (radians)
/// date1 double TDB as a 2-part...
/// date2 double ...Julian Date (Note 1)
/// ```
///
/// Returned:
/// ```
/// rc,dc double ICRS astrometric RA,Dec (radians)
/// eo double equation of the origins (ERA-GST, radians, Note 4)
/// ```
/// Notes:
///
/// 1) The TDB date date1+date2 is a Julian Date, apportioned in any
/// convenient way between the two arguments. For example,
/// JD(TDB)=2450123.7 could be expressed in any of these ways, among
/// others:
/// ```
///
/// date1 date2
///
/// 2450123.7 0.0 (JD method)
/// 2451545.0 -1421.3 (J2000 method)
/// 2400000.5 50123.2 (MJD method)
/// 2450123.5 0.2 (date & time method)
/// ```
/// The JD method is the most natural and convenient to use in cases
/// where the loss of several decimal digits of resolution is
/// acceptable. The J2000 method is best matched to the way the
/// argument is handled internally and will deliver the optimum
/// resolution. The MJD method and the date & time methods are both
/// good compromises between resolution and convenience. For most
/// applications of this function the choice will not be at all
/// critical.
///
/// TT can be used instead of TDB without any significant impact on
/// accuracy.
///
/// 2) Iterative techniques are used for the aberration and light
/// deflection corrections so that the functions iauAtic13 (or
/// iauAticq) and iauAtci13 (or iauAtciq) are accurate inverses;
/// even at the edge of the Sun's disk the discrepancy is only about
/// 1 nanoarcsecond.
///
/// 3) The available accuracy is better than 1 milliarcsecond, limited
/// mainly by the precession-nutation model that is used, namely
/// IAU 2000A/2006. Very close to solar system bodies, additional
/// errors of up to several milliarcseconds can occur because of
/// unmodeled light deflection; however, the Sun's contribution is
/// taken into account, to first order. The accuracy limitations of
/// the SOFA function iauEpv00 (used to compute Earth position and
/// velocity) can contribute aberration errors of up to
/// 5 microarcseconds. Light deflection at the Sun's limb is
/// uncertain at the 0.4 mas level.
///
/// 4) Should the transformation to (equinox based) J2000.0 mean place
/// be required rather than (CIO based) ICRS coordinates, subtract the
/// equation of the origins from the returned right ascension:
/// RA = RI - EO. (The iauAnp function can then be applied, as
/// required, to keep the result in the conventional 0-2pi range.)
///
/// Called:
/// ```
/// iauApci13 astrometry parameters, ICRS-CIRS, 2013
/// iauAticq quick CIRS to ICRS astrometric
/// ```