On Wed, Jan 11, 2017 at 5:03 PM, Warner Losh <[email protected]> wrote: > On Wed, Jan 11, 2017 at 3:28 PM, Zefram <[email protected]> wrote: >> It would be nice to have more sophisticated projections from IERS more >> than a year ahead. It would particularly help in evaluating the proposals >> that have been made involving scheduling leap seconds further ahead. > > Especially if they had error bars that reflect the current confidence > levels, perhaps tested on historic data.
It might also be helpful if we understood better how these models are used to decide when to announce leap seconds. I don't know currently what criteria the IERS uses, except the overall parameters of keeping |UT1-UTC| < 0.9 s and preferring to have leap seconds in June or December instead of other months. For example, here's Bulletin A from 2016-06-30: https://datacenter.iers.org/eop/-/somos/5Rgv/getTX/6/bulletina-xxix-026.txt 2016-12-31 (MJD 57753): -0.45079 s 2017-06-30 (MJD 57934): -0.73759 s You might have expected either of these days to have leap seconds. The next week, Bulletin C Number 52 announced a leap second for 2016-12-31. The actual value of UT1-UTC on that day was about -0.407858 s. The predictions looked similar on 2014-06-26: https://datacenter.iers.org/eop/-/somos/5Rgv/getTX/6/bulletina-xxvii-026.txt 2014-12-31 (MJD 57022): -0.46583 s 2015-06-26 (MJD 57199): -0.67258 s Again, either December 2014 or June 2015 could have had leap seconds. But in this case the leap second was deferred. It happened on 2015-06-30, when UT1-UTC was -0.6760362 s (https://datacenter.iers.org/eop/-/somos/5Rgv/getTX/207/bulletinb-330.txt). _______________________________________________ LEAPSECS mailing list [email protected] https://pairlist6.pair.net/mailman/listinfo/leapsecs
