The TT subscript indicates that for this formula, the Julian date should use the Terrestrial Time scale, or its predecessor, ephemeris time.
12.
As UT is slightly irregular in its rate, astronomers introduced Ephemeris Time, which has since been replaced by Terrestrial Time ( TT ).
13.
Atomic clock Calendar Chinese calendar Computus Diwali Ephemeris time Hertz Intellectual history of time Julian date Season
14.
This was in conformity with the ephemeris time scale adopted by the Brown's Tables of the Moon ( used from 1923 through 1983 ).
15.
After the caesium atomic clock was invented, such clocks were used increasingly from the late 1950s as secondary realizations of ephemeris time ( ET ).
16.
For continuity with its predecessor Ephemeris Time, TCB was set to match ET at around Julian Date 2443144.5 ( 1977-01-01T00Z ).
17.
For continuity with its predecessor Ephemeris Time, TCG was set to match ET at around Julian Date 2443144.5 ( 1977-01-01T00Z ).
18.
By the middle of the 20th century, the difference between Universal and Ephemeris Time had been recognised and evaluated, and the troublesome empirical terms were removed.
19.
In the meantime, Brown's theory was improved with better constants and the introduction of Ephemeris Time and the removal of some empirical corrections associated with this.
20.
For continuity with their predecessor Ephemeris Time ( ET ), TT and TCG were set to match ET at around Julian Date ( 1977-01-01T00Z ).
