slaGmst -

SYNOPSYS

PARAMETERS

double ut1

DESCRIPTION

  Conversion from Universal Time to Sidereal Time.

  (double precision)

Given

    ut1    double     Universal Time (strictly UT1) expressed as
                      Modified Julian Date (JD-2400000.5)

  The result is the Greenwich Mean Sidereal Time (double
  precision, radians).

  The IAU 1982 expression (see page S15 of the 1984 Astronomical
  Almanac) is used, but rearranged to reduce rounding errors.
  This expression is always described as giving the GMST at
  0 hours UT.  In fact, it gives the difference between the
  GMST and the UT, which happens to equal the GMST (modulo
  24 hours) at 0 hours UT each day.  In this routine, the
  fractional UT is used directly as the argument for the
  standard formula, and the fractional part of the UT is
  added separately;  note that the factor 1.0027379... does
  not appear.

Called

 slaDranrm

  Defined in slamac.h:  D2PI, DS2R

  P.T.Wallace   Starlink   10 December 1993

SEE ALSO

• slalib.3