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.help dat Jun99 "Slalib Package"
.nf
DOUBLE PRECISION FUNCTION slDAT (UTC)
- - - -
D A T
- - - -
Increment to be applied to Coordinated Universal Time UTC to give
International Atomic Time TAI (double precision)
Given:
UTC d UTC date as a modified JD (JD-2400000.5)
Result: TAI-UTC in seconds
Notes:
1 The UTC is specified to be a date rather than a time to indicate
that care needs to be taken not to specify an instant which lies
within a leap second. Though in most cases UTC can include the
fractional part, correct behaviour on the day of a leap second
can only be guaranteed up to the end of the second 23:59:59.
2 For epochs from 1961 January 1 onwards, the expressions from the
file ftp://maia.usno.navy.mil/ser7/tai-utc.dat are used.
3 The 5ms timestep at 1961 January 1 is taken from 2.58.1 (p87) of
the 1992 Explanatory Supplement.
4 UTC began at 1960 January 1.0 (JD 2436934.5) and it is improper
to call the routine with an earlier epoch. However, if this
is attempted, the TAI-UTC expression for the year 1960 is used.
:-----------------------------------------:
: :
: IMPORTANT :
: :
: This routine must be updated on each :
: occasion that a leap second is :
: announced :
: :
: Latest leap second: 1999 January 1 :
: :
:-----------------------------------------:
P.T.Wallace Starlink 31 May 1999
Copyright (C) 1999 Rutherford Appleton Laboratory
Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
.fi
.endhelp
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