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Diffstat (limited to 'src/slalib/dat.f')
| -rw-r--r-- | src/slalib/dat.f | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/src/slalib/dat.f b/src/slalib/dat.f new file mode 100644 index 0000000..423e59b --- /dev/null +++ b/src/slalib/dat.f @@ -0,0 +1,219 @@ + DOUBLE PRECISION FUNCTION sla_DAT (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 +*- + + IMPLICIT NONE + + DOUBLE PRECISION UTC + + DOUBLE PRECISION DT + + + + IF (.FALSE.) THEN + +* - - - - - - - - - - - - - - - - - - - - - - * +* Add new code here on each occasion that a * +* leap second is announced, and update the * +* preamble comments appropriately. * +* - - - - - - - - - - - - - - - - - - - - - - * + +* 1999 January 1 + ELSE IF (UTC.GE.51179D0) THEN + DT=32D0 + +* 1997 July 1 + ELSE IF (UTC.GE.50630D0) THEN + DT=31D0 + +* 1996 January 1 + ELSE IF (UTC.GE.50083D0) THEN + DT=30D0 + +* 1994 July 1 + ELSE IF (UTC.GE.49534D0) THEN + DT=29D0 + +* 1993 July 1 + ELSE IF (UTC.GE.49169D0) THEN + DT=28D0 + +* 1992 July 1 + ELSE IF (UTC.GE.48804D0) THEN + DT=27D0 + +* 1991 January 1 + ELSE IF (UTC.GE.48257D0) THEN + DT=26D0 + +* 1990 January 1 + ELSE IF (UTC.GE.47892D0) THEN + DT=25D0 + +* 1988 January 1 + ELSE IF (UTC.GE.47161D0) THEN + DT=24D0 + +* 1985 July 1 + ELSE IF (UTC.GE.46247D0) THEN + DT=23D0 + +* 1983 July 1 + ELSE IF (UTC.GE.45516D0) THEN + DT=22D0 + +* 1982 July 1 + ELSE IF (UTC.GE.45151D0) THEN + DT=21D0 + +* 1981 July 1 + ELSE IF (UTC.GE.44786D0) THEN + DT=20D0 + +* 1980 January 1 + ELSE IF (UTC.GE.44239D0) THEN + DT=19D0 + +* 1979 January 1 + ELSE IF (UTC.GE.43874D0) THEN + DT=18D0 + +* 1978 January 1 + ELSE IF (UTC.GE.43509D0) THEN + DT=17D0 + +* 1977 January 1 + ELSE IF (UTC.GE.43144D0) THEN + DT=16D0 + +* 1976 January 1 + ELSE IF (UTC.GE.42778D0) THEN + DT=15D0 + +* 1975 January 1 + ELSE IF (UTC.GE.42413D0) THEN + DT=14D0 + +* 1974 January 1 + ELSE IF (UTC.GE.42048D0) THEN + DT=13D0 + +* 1973 January 1 + ELSE IF (UTC.GE.41683D0) THEN + DT=12D0 + +* 1972 July 1 + ELSE IF (UTC.GE.41499D0) THEN + DT=11D0 + +* 1972 January 1 + ELSE IF (UTC.GE.41317D0) THEN + DT=10D0 + +* 1968 February 1 + ELSE IF (UTC.GE.39887D0) THEN + DT=4.2131700D0+(UTC-39126D0)*0.002592D0 + +* 1966 January 1 + ELSE IF (UTC.GE.39126D0) THEN + DT=4.3131700D0+(UTC-39126D0)*0.002592D0 + +* 1965 September 1 + ELSE IF (UTC.GE.39004D0) THEN + DT=3.8401300D0+(UTC-38761D0)*0.001296D0 + +* 1965 July 1 + ELSE IF (UTC.GE.38942D0) THEN + DT=3.7401300D0+(UTC-38761D0)*0.001296D0 + +* 1965 March 1 + ELSE IF (UTC.GE.38820D0) THEN + DT=3.6401300D0+(UTC-38761D0)*0.001296D0 + +* 1965 January 1 + ELSE IF (UTC.GE.38761D0) THEN + DT=3.5401300D0+(UTC-38761D0)*0.001296D0 + +* 1964 September 1 + ELSE IF (UTC.GE.38639D0) THEN + DT=3.4401300D0+(UTC-38761D0)*0.001296D0 + +* 1964 April 1 + ELSE IF (UTC.GE.38486D0) THEN + DT=3.3401300D0+(UTC-38761D0)*0.001296D0 + +* 1964 January 1 + ELSE IF (UTC.GE.38395D0) THEN + DT=3.2401300D0+(UTC-38761D0)*0.001296D0 + +* 1963 November 1 + ELSE IF (UTC.GE.38334D0) THEN + DT=1.9458580D0+(UTC-37665D0)*0.0011232D0 + +* 1962 January 1 + ELSE IF (UTC.GE.37665D0) THEN + DT=1.8458580D0+(UTC-37665D0)*0.0011232D0 + +* 1961 August 1 + ELSE IF (UTC.GE.37512D0) THEN + DT=1.3728180D0+(UTC-37300D0)*0.001296D0 + +* 1961 January 1 + ELSE IF (UTC.GE.37300D0) THEN + DT=1.4228180D0+(UTC-37300D0)*0.001296D0 + +* Before that + ELSE + DT=1.4178180D0+(UTC-37300D0)*0.001296D0 + + END IF + + sla_DAT=DT + + END |