atccq¶
- erfa.atccq(rc, dc, pr, pd, px, rv, astrom)[source]¶
Quick transformation of a star’s ICRS catalog entry (epoch J2000.0) into ICRS astrometric place, given precomputed star-independent astrometry parameters.
- Parameters:
- rcdouble array
- dcdouble array
- prdouble array
- pddouble array
- pxdouble array
- rvdouble array
- astromeraASTROM array
- Returns:
- radouble array
- dadouble array
Notes
Wraps ERFA function
eraAtccq
. The ERFA documentation is:- - - - - - - - - e r a A t c c q - - - - - - - - - Quick transformation of a star's ICRS catalog entry (epoch J2000.0) into ICRS astrometric place, given precomputed star-independent astrometry parameters. Use of this function is appropriate when efficiency is important and where many star positions are to be transformed for one date. The star-independent parameters can be obtained by calling one of the functions eraApci[13], eraApcg[13], eraApco[13] or eraApcs[13]. If the parallax and proper motions are zero the transformation has no effect. Given: rc,dc double ICRS RA,Dec at J2000.0 (radians) pr double RA proper motion (radians/year, Note 3) pd double Dec proper motion (radians/year) px double parallax (arcsec) rv double radial velocity (km/s, +ve if receding) astrom eraASTROM* star-independent astrometry parameters: pmt double PM time interval (SSB, Julian years) eb double[3] SSB to observer (vector, au) eh double[3] Sun to observer (unit vector) em double distance from Sun to observer (au) v double[3] barycentric observer velocity (vector, c) bm1 double sqrt(1-|v|^2): reciprocal of Lorenz factor bpn double[3][3] bias-precession-nutation matrix along double longitude + s' (radians) xpl double polar motion xp wrt local meridian (radians) ypl double polar motion yp wrt local meridian (radians) sphi double sine of geodetic latitude cphi double cosine of geodetic latitude diurab double magnitude of diurnal aberration vector eral double "local" Earth rotation angle (radians) refa double refraction constant A (radians) refb double refraction constant B (radians) Returned: ra,da double ICRS astrometric RA,Dec (radians) Notes: 1) All the vectors are with respect to BCRS axes. 2) Star data for an epoch other than J2000.0 (for example from the Hipparcos catalog, which has an epoch of J1991.25) will require a preliminary call to eraPmsafe before use. 3) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt. Called: eraPmpx proper motion and parallax eraC2s p-vector to spherical eraAnp normalize angle into range 0 to 2pi This revision: 2021 April 18 Copyright (C) 2013-2023, NumFOCUS Foundation. Derived, with permission, from the SOFA library. See notes at end of file.