[LEAPSECS] Notation for transmitted vs. paper time scales

Tom Van Baak tvb at LeapSecond.com
Wed Nov 5 21:08:37 EST 2014

> if you are trying to measure UT1, it still takes time to correlate
> the VLBI data and reduce it, and then send the results
> to the right people, which doesn't happen without delay. (pardon
> the pun). Synching up cesiums, hydrogen masers, and rubidium
> fountains can happen much faster than it used to of course.

Hi Greg,

For those that need daily values of UT1, IERS does a fantastic job with both high-accuracy currently measured values, as well as very accurate predictions of values in the near future. The accuracy declines as the prediction interval goes from days to weeks to months. All this is carefully documented in their servers.

I'm not sure what you mean about syncing faster -- cesiums, hydrogen masers, and rubidium fountains are usually not physically steered. Instead external synthesizers do gradual phase or frequency steering, at extremely small rates like 1e-15 or -16 or -17. This is millions of times below daily irregularities of Earth rotation rate (1e-9).


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