[fitsbits] Re: leap second alert

[Patrick Wallace]

On 15 Dec 1999, Paul Schlyter wrote:

>       Usually one means UT2 when saying UT.

I think UT1 is the more usual meaning.

> TDB = Barycentric Dynamical Time. Used as a time-scale of ephemerides
>       referred to the barycentre of the solar system. Differs from TDT
>       by at most a few milliseconds.

About 1.6 ms.

> TT  = Terrestial Time. Used instead of TDT or TDB when the difference
>       between them doesn't matter.

TT and TDT are synonymous.


Patrick Wallace
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