epj¶
- erfa.epj(dj1, dj2)[source]¶
Julian Date to Julian Epoch.
- Parameters:
- dj1double array
- dj2double array
- Returns:
- c_retvaldouble array
Notes
Wraps ERFA function
eraEpj
. The ERFA documentation is:- - - - - - - e r a E p j - - - - - - - Julian Date to Julian Epoch. Given: dj1,dj2 double Julian Date (Note 4) Returned (function value): double Julian Epoch Notes: 1) Julian Epoch is a method of expressing a moment in time as a year plus fraction. 2) Julian Epoch J2000.0 is 2000 Jan 1.5, and the length of the year is 365.25 days. 3) For historical reasons, the time scale formally associated with Julian Epoch is TDB (or TT, near enough). However, Julian Epoch can be used more generally as a calendrical convention to represent other time scales such as TAI and TCB. This is analogous to Julian Date, which was originally defined specifically as a way of representing Universal Times but is now routinely used for any of the regular time scales. 4) The Julian Date is supplied in two pieces, in the usual ERFA manner, which is designed to preserve time resolution. The Julian Date is available as a single number by adding dj1 and dj2. The maximum resolution is achieved if dj1 is 2451545.0 (J2000.0). Reference: Lieske, J.H., 1979, Astron.Astrophys. 73, 282. This revision: 2022 May 6 Copyright (C) 2013-2023, NumFOCUS Foundation. Derived, with permission, from the SOFA library. See notes at end of file.