Paul Hirose wrote: > Thinking I had missed a pending leap second, I checked the IERS site, > but Bulletin C says the offset is still 37 seconds and nothing is > scheduled. ???
The GPS satellites transmit the week number of the nearest leap second (WNlsf) as 8 bit value only, giving a valid range of ~+/- 128 weeks from "now". The last leap second was on 2016-12-31, and counting the number of weeks in 2017, 2018, and 2019 until now, this sounds like close to 128. I haven't computed the exact number, but I'm assuming that the range was just recently exceeded. I'm currently out of the office, but I've heard from my colleagues that the currently sent WNlsf number is 0x89. However, the current GPS/UTC offset numbers before and after the nearest leap seconds are still 18/18, so there is no current leap second announcement, and WNlsf may be ambiguous. When the next announcement starts the offsets will change to 18/19, and WNlsf will also be updated to be in range. The "mbgstatus -vvv" program for the Meinberg GPS PCI cards now shows a wrong leap second date for 2021, too: UTC correction parameters: t0t: 2057|405504.0000000, A0: -9.31323e-10 A1: -2.66454e-15 WNlsf: 2185, DN: 7, offs: 18/18 Last leap second eventually at UTC midnight at the end of Sat, 2021-11-27 while just recently the displayed leap second date was (correctly) 2016-12-31. However, Meinberg GPS receivers evaluate WNlsf *only* if the 2 offset values differ, i.e. there is really an announcement of a leap second, and WNlsf is in a valid range, so these receivers don't have a problem with a wrong leap second. If no leap second is announced then extended week number and thus the date *can* be wrong, but it's just informational, and the word "eventually" is used to point out the ambiguity. Martin _______________________________________________ LEAPSECS mailing list [email protected] https://pairlist6.pair.net/mailman/listinfo/leapsecs
