On 2022-11-21 14:19, Seaman, Robert Lewis - (rseaman) wrote:
In a post-leap-second world, precision values for dUT1 either become more
critical or less. Or rather, they become no-less important scientifically but
perhaps negligible politically. For
example,https://www.sciencedirect.com/science/article/pii/S0273117719302388
says “Global Navigation Satellite Systems (GNSS) are dependent on VLBI as they
need dUT1 to maintain its operability”.
I am not sure if we mean the same thing by "dUT1". I used
it in the sense:
dUT1 is an additonal correction to UTC so that
UTC + DUT1 + dUT1
is a better approximation of UT1 than just
UTC + DUT1
and takes its values in the set {0, ±20, ±40, ±60, ±80} ms.
dUT1 in this sense is used only by some Russian time signals,
and its value is not defined by the IERS. Moreover, since the
amplitude of UT1 - UT2 is about 34 ms, dUT1 must be adjusted
for annual variations of UT1 - UTC.
I have seen the term "dUT1" to be used for ΔUT1 = UT1 - UTC
(and that is how I read it in the paper you quoted), and
also for the rate d(UT1) -- but these are different beasts.
Michael Deckers.
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