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# taiutc

erfa.taiutc(tai1, tai2)

  Time scale transformation: International Atomic Time, TAI, to Coordinated Universal Time, UTC.

  Parameters:
    tai1 double array
    tai2 double array
  Returns:
    utc1 double array
    utc2 double array

  Notes

  Wraps ERFA function `eraTaiutc`. The ERFA documentation is:

      - - - - - - - - - -
       e r a T a i u t c
      - - - - - - - - - -

      Time scale transformation:  International Atomic Time, TAI, to
      Coordinated Universal Time, UTC.

      Given:
         tai1,tai2  double   TAI as a 2-part Julian Date (Note 1)

      Returned:
         utc1,utc2  double   UTC as a 2-part quasi Julian Date (Notes 1-3)

      Returned (function value):
                    int      status: +1 = dubious year (Note 4)
                                      0 = OK
                                     -1 = unacceptable date

      Notes:

      1) tai1+tai2 is Julian Date, apportioned in any convenient way
         between the two arguments, for example where tai1 is the Julian
         Day Number and tai2 is the fraction of a day.  The returned utc1
         and utc2 form an analogous pair, except that a special convention
         is used, to deal with the problem of leap seconds - see the next
         note.

      2) JD cannot unambiguously represent UTC during a leap second unless
         special measures are taken.  The convention in the present
         function is that the JD day represents UTC days whether the
         length is 86399, 86400 or 86401 SI seconds.  In the 1960-1972 era
         there were smaller jumps (in either direction) each time the
         linear UTC(TAI) expression was changed, and these "mini-leaps"
         are also included in the ERFA convention.

      3) The function eraD2dtf can be used to transform the UTC quasi-JD
         into calendar date and clock time, including UTC leap second
         handling.

      4) The warning status "dubious year" flags UTCs that predate the
         introduction of the time scale or that are too far in the future
         to be trusted.  See eraDat for further details.

      Called:
         eraUtctai    UTC to TAI

      References:

         McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
         IERS Technical Note No. 32, BKG (2004)

         Explanatory Supplement to the Astronomical Almanac,
         P. Kenneth Seidelmann (ed), University Science Books (1992)

      This revision:  2021 May 11

      Copyright (C) 2013-2023, NumFOCUS Foundation.
      Derived, with permission, from the SOFA library.  See notes at end of file.