[LEAPSECS] trivia, the 2nd longest year

[Michael Deckers]

   On 2012-04-12 19:33, Steve Allen asked:


> A well circulated piece of trivia is that 1972 was the longest year in

> recorded history because civil time contained two leap seconds.

>

> I offer this challenge:

>

> What was the second longest year in recorded history, and how many

> leap seconds did it have?


   After 1972, UTC was never delayed against TAI by more than 1 s
   per year. And before 1972 (and after 1960 when UTC was started),
   this happened only once, in 1971, when UTC was delayed against TAI
   by 1.053 838 s (the rate d(TAI)/d(UTC) was 1 + 2.592 ms/d at that
   time).

   But of course, this does not answer your question because
   during "the year" 1971 (the time when UTC indicated 1971, plus
   the time span of about 107.757 997 ms in UTC when UTC was >= 1972
   but before TAI reached 1972 + 10 s), TAI only gained about
   365 d + 1.05 s which is nearly a day less than what TAI gains
   in any leap year of UTC.

   So the expected answer probably is any leap year > 1972 with a
   positive leap second (1976, 1992, 2008, 2012), where one may
   even remark that, in terms of the TT time scale, 2008 and 2012
   are slightly longer than 1976 and 1992, and that 2012 may not
   belong to recorded history yet.

   Or you mean a year before 1960 but then it is not clear to me
   which time scale you use for determining the years (instead
   of UTC) and which to measure their lengths (instead of TAI).

   Michael Deckers.