tcbtdb¶
- erfa.tcbtdb(tcb1, tcb2)[source]¶
Time scale transformation: Barycentric Coordinate Time, TCB, to Barycentric Dynamical Time, TDB.
- Parameters:
- tcb1double array
- tcb2double array
- Returns:
- tdb1double array
- tdb2double array
Notes
Wraps ERFA function
eraTcbtdb
. The ERFA documentation is:- - - - - - - - - - e r a T c b t d b - - - - - - - - - - Time scale transformation: Barycentric Coordinate Time, TCB, to Barycentric Dynamical Time, TDB. Given: tcb1,tcb2 double TCB as a 2-part Julian Date Returned: tdb1,tdb2 double TDB as a 2-part Julian Date Returned (function value): int status: 0 = OK Notes: 1) tcb1+tcb2 is Julian Date, apportioned in any convenient way between the two arguments, for example where tcb1 is the Julian Day Number and tcb2 is the fraction of a day. The returned tdb1,tdb2 follow suit. 2) The 2006 IAU General Assembly introduced a conventional linear transformation between TDB and TCB. This transformation compensates for the drift between TCB and terrestrial time TT, and keeps TDB approximately centered on TT. Because the relationship between TT and TCB depends on the adopted solar system ephemeris, the degree of alignment between TDB and TT over long intervals will vary according to which ephemeris is used. Former definitions of TDB attempted to avoid this problem by stipulating that TDB and TT should differ only by periodic effects. This is a good description of the nature of the relationship but eluded precise mathematical formulation. The conventional linear relationship adopted in 2006 sidestepped these difficulties whilst delivering a TDB that in practice was consistent with values before that date. 3) TDB is essentially the same as Teph, the time argument for the JPL solar system ephemerides. Reference: IAU 2006 Resolution B3 This revision: 2021 May 11 Copyright (C) 2013-2023, NumFOCUS Foundation. Derived, with permission, from the SOFA library. See notes at end of file.