On Thu, 2022-05-05 at 20:05 +0100, Tony Finch wrote: > John Sauter via LEAPSECS <[email protected]> wrote: > > > > One of the links on that page is to the draft of the resolutions > > for > > the 27th CGPM meeting, in November 2022. Resolution D notes that > > "recent observations on the rotation rate of the Earth indicate the > > possible need for the first negative leap second whose insertion > > has > > never been foreseen or tested". However, they are calling for an > > increase in the maximum value of UT1-UTC by 2035, which would be > > too > > late to avoid the negative leap second, if current predictions hold > > up. > > I have just got today's Bulletin A. The LoD term in the equation for > more > distant estimates of UT1-UTC is now 24h - 280 µs, down from -270 µs > last > week. It has been dropping rapidly again since March, after > increasing > slowly for half a year.. > > My guesstimate for the negative leap second is now end of 2027, and > likely > to get closer if things continue like this! >
To illustrate Tony's point, here is a plot of the slope of the IERS's
estimates of UT2-UTC since 2005. Values greater than zero predict a
negative leap second. UT2 is UT1 with seasonal fluctuations removed.
John Sauter ([email protected])
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UT2_slope.pdf
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