Re: [LEAPSECS] Never mind DUT1, what happened to dX ?
On Tue 2022-03-08T15:30:37+ Tony Finch hath writ: > (note that the coefficient is seconds _shorter_ than 24*60*60µss, > so +0.00021 means the long-term average LoD is 24h-210µs) Ah, that points out what may be a cool correlation. Looking back at dX and dY over their relatively short history it may be the case that the celestial pole position wobble around the predictable position is smaller when the rotation is accelerating. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Never mind DUT1, what happened to dX ?
Poul-Henning Kamp wrote: > I looked at the Bulletin A plots this morning to see how DUT1 is > developing, but then I noticed the 'dX' term plot: > > > https://datacenter.iers.org/singlePlot.php?plotname=BulletinA_All-DX=6 > > What happened in late 2019 ? I use the long-term prediction formula from Bulletin A as my LoD benchmark, since it omits the short term and seasonal variations. PREDICTIONS: The following formulas will not reproduce the predictions given below, but may be used to extend the predictions beyond the end of this table. x = 0.1405 - 0.1018 cos A - 0.0061 sin A - 0.0185 cos C + 0.0280 sin C y = 0.3550 - 0.0065 cos A + 0.0923 sin A + 0.0280 cos C + 0.0185 sin C UT1-UTC = -0.0891 + 0.00021 (MJD - 59649) - (UT2-UT1) ^^^ (note that the coefficient is seconds _shorter_ than 24*60*60µss, so +0.00021 means the long-term average LoD is 24h-210µs) It was fairly steady at 24h+700µs ish through 2018 and 2019, but it started decreasing by about 10µs per week in July 2019, bottoming out at 24h-260µs in May last year. That is, the speedup started at about the same time as the anomaly you pointed out. The LoD was creeping up: it was 24h-200µs Dec-Feb but in recent weeks it is down to 24h-210µs again... -- Tony Finchhttps://dotat.at/ Great Orme Head to the Mull of Galloway: South or southeast 6 to gale 8, decreasing 4 to 6 for a time. Slight or moderate, occasionally rough in northwest. Rain or showers at first. Good, occasionally moderate at first.___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Never mind DUT1, what happened to dX ?
On Mon 2022-03-07T06:57:02+ Poul-Henning Kamp hath writ: > I'm not talking about the two spikes, I'm talking about the oscillation > disappearing, > and that seems to be in all the data sources ? ah, yes. I think we need another nutation cycle worth of high precision data, but I suspect nothing unusual is happening. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Never mind DUT1, what happened to dX ?
Steve Allen writes: > On Mon 2022-03-07T06:33:31+ Poul-Henning Kamp hath writ: > > I looked at the Bulletin A plots this morning to see how DUT1 is > > developing, but then I noticed the 'dX' term plot: > > > > > > https://datacenter.iers.org/singlePlot.php?plotname=BulletinA_All-DX=6 > > > > What happened in late 2019 ? > > 2019 October is when USNO had to take their machines offline due to > new security requirements. But why would that affect only the dX plot ? > Those artifacts do not show at the ObsPM site > https://hpiers.obspm.fr/eop-pc/index.php?index=analysis=en I'm not talking about the two spikes, I'm talking about the oscillation disappearing, and that seems to be in all the data sources ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Never mind DUT1, what happened to dX ?
On Mon 2022-03-07T06:33:31+ Poul-Henning Kamp hath writ: > I looked at the Bulletin A plots this morning to see how DUT1 is > developing, but then I noticed the 'dX' term plot: > > > https://datacenter.iers.org/singlePlot.php?plotname=BulletinA_All-DX=6 > > What happened in late 2019 ? 2019 October is when USNO had to take their machines offline due to new security requirements. Those artifacts do not show at the ObsPM site https://hpiers.obspm.fr/eop-pc/index.php?index=analysis=en -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
