FR should record all events in UTC, which is different form GPS-time, as
UTC has leap seconds and GPS-time does not.

UTC and GPS-time were identical at UTC midnight the night from 5th of
Jan 1980 to 6th of Jan 1980.

Leap Seconds inserted into the UTC Time Scale

Date MJD Date MJD Date MJD Date MJD
2005-12-31 53735 1998-12-31 51178 1989-12-31 47891 1979-12-31 44238
1997-06-30 50629 1987-12-31 47160 1978-12-31 43873
1995-12-31 50082 1985-06-30 46246 1977-12-31 43508
1994-06-30 49533 1983-06-30 45515 1976-12-31 43143
1993-06-30 49168 1982-06-30 45150 1975-12-31 42777
1992-06-30 48803 1981-06-30 44785 1974-12-31 42412
1990-12-31 48256 1973-12-31 42047
1972-12-31 41682
1972-06-30 41498