era00¶
- erfa.era00(dj1, dj2)[source]¶
Earth rotation angle (IAU 2000 model).
- Parameters:
- dj1double array
- dj2double array
- Returns:
- c_retvaldouble array
Notes
Wraps ERFA function
eraEra00
. The ERFA documentation is:- - - - - - - - - e r a E r a 0 0 - - - - - - - - - Earth rotation angle (IAU 2000 model). Given: dj1,dj2 double UT1 as a 2-part Julian Date (see note) Returned (function value): double Earth rotation angle (radians), range 0-2pi Notes: 1) The UT1 date dj1+dj2 is a Julian Date, apportioned in any convenient way between the arguments dj1 and dj2. For example, JD(UT1)=2450123.7 could be expressed in any of these ways, among others: dj1 dj2 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 and MJD methods are good compromises between resolution and convenience. The date & time method is best matched to the algorithm used: maximum precision is delivered when the dj1 argument is for 0hrs UT1 on the day in question and the dj2 argument lies in the range 0 to 1, or vice versa. 2) The algorithm is adapted from Expression 22 of Capitaine et al. 2000. The time argument has been expressed in days directly, and, to retain precision, integer contributions have been eliminated. The same formulation is given in IERS Conventions (2003), Chap. 5, Eq. 14. Called: eraAnp normalize angle into range 0 to 2pi References: Capitaine N., Guinot B. and McCarthy D.D, 2000, Astron. Astrophys., 355, 398-405. McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), IERS Technical Note No. 32, BKG (2004) This revision: 2021 May 11 Copyright (C) 2013-2021, NumFOCUS Foundation. Derived, with permission, from the SOFA library. See notes at end of file.