sofars/astro/
atccq.rs

1use super::{IauAstrom, pmpx};
2use crate::vm::{anp, c2s};
3
4///  Quick catalog −> astrometric
5///
6///  Quick transformation of a star's ICRS catalog entry (epoch J2000.0)
7///  into ICRS astrometric place, given precomputed star-independent
8///  astrometry parameters.
9///
10///  Use of this function is appropriate when efficiency is important and
11///  where many star positions are to be transformed for one date.  The
12///  star-independent parameters can be obtained by calling one of the
13///  functions iauApci[13], iauApcg[13], iauApco[13] or iauApcs[13].
14///
15///  If the parallax and proper motions are zero the transformation has
16///  no effect.
17///
18///  This function is part of the International Astronomical Union's
19///  SOFA (Standards of Fundamental Astronomy) software collection.
20///
21///  Status:  support function.
22///
23///  Given:
24///  ```
25///     rc,dc  double     ICRS RA,Dec at J2000.0 (radians)
26///     pr     double     RA proper motion (radians/year, Note 3)
27///     pd     double     Dec proper motion (radians/year)
28///     px     double     parallax (arcsec)
29///     rv     double     radial velocity (km/s, +ve if receding)
30///     astrom iauASTROM* star-independent astrometry parameters:
31///      pmt    double       PM time interval (SSB, Julian years)
32///      eb     double[3]    SSB to observer (vector, au)
33///      eh     double[3]    Sun to observer (unit vector)
34///      em     double       distance from Sun to observer (au)
35///      v      double[3]    barycentric observer velocity (vector, c)
36///      bm1    double       sqrt(1-|v|^2): reciprocal of Lorenz factor
37///      bpn    double[3][3] bias-precession-nutation matrix
38///      along  double       longitude + s' (radians)
39///      xpl    double       polar motion xp wrt local meridian (radians)
40///      ypl    double       polar motion yp wrt local meridian (radians)
41///      sphi   double       sine of geodetic latitude
42///      cphi   double       cosine of geodetic latitude
43///      diurab double       magnitude of diurnal aberration vector
44///      eral   double       "local" Earth rotation angle (radians)
45///      refa   double       refraction constant A (radians)
46///      refb   double       refraction constant B (radians)
47///  ```
48///  Returned:
49///  ```
50///     ra,da  double*    ICRS astrometric RA,Dec (radians)
51///  ```
52///  Notes:
53///
54///  1) All the vectors are with respect to BCRS axes.
55///
56///  2) Star data for an epoch other than J2000.0 (for example from the
57///     Hipparcos catalog, which has an epoch of J1991.25) will require a
58///     preliminary call to iauPmsafe before use.
59///
60///  3) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt.
61///
62///  Called:
63///  ```
64///     iauPmpx      proper motion and parallax
65///     iauC2s       p-vector to spherical
66///     iauAnp       normalize angle into range 0 to 2pi
67///  ```
68pub fn atccq(
69    rc: f64,
70    dc: f64,
71    pr: f64,
72    pd: f64,
73    px: f64,
74    rv: f64,
75    astrom: &IauAstrom,
76) -> (f64, f64) {
77    /* Proper motion and parallax, giving BCRS coordinate direction. */
78    let p = pmpx(rc, dc, pr, pd, px, rv, astrom.pmt, astrom.eb);
79
80    /* ICRS astrometric RA,Dec. */
81    let (w, da) = c2s(&p);
82    let ra = anp(w);
83
84    (ra, da)
85}
sofars/astro/atccq.rs

sofars/astro/
atccq.rs
