SLA_DTT

TT minus UTC

ACTION:: Compute $Δ$ TT, the increment to be applied to Coordinated Universal Time UTC to give Terrestrial Time TT.
CALL:: D = sla_DTT (DJU)

DJU	D	UTC date as a modified JD (JD $-$ 2400000.5)

sla_DTT	D	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 be guaranteed only up to the end of the second $2 3^{h} 5 9^{m} 5 9^{s}$ .
(2): Pre 1972 January 1 a fixed value of 10 + ET $-$ TAI is returned.
(3): TT is one interpretation of the defunct time scale Ephemeris Time, ET.
(4): See also the routine sla_DT, which roughly estimates ET $-$ UT for historical epochs.