#include "slalib.h" #include "slamac.h" double slaDtt ( double utc ) /* ** - - - - - - - ** s l a D t t ** - - - - - - - ** ** Increment to be applied to Coordinated Universal Time UTC to give ** Terrestrial Time TT (formerly Ephemeris Time ET). ** ** (double precision) ** ** Given: ** utc double UTC date as a modified JD (JD-2400000.5) ** ** Result: TT-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 Pre 1972 January 1 a fixed value of 10 + ET-TAI is returned. ** ** 3 See also the routine slaDt, which roughly estimates ET-UT for ** historical epochs. ** ** Called: slaDat ** ** Last revision: 6 December 1994 ** ** Copyright P.T.Wallace. All rights reserved. */ { return 32.184 + slaDat ( utc ); }