[tz] New Yorker article on David Mills and NTP

[Brooks Harris]

On 2022-10-04 5:20 PM, Paul Eggert via tz wrote:
>
> Predicting length of day (LOD) is a tricky business with no real 
> consensus.
I think that statement is a little misleading.

While there is no specification for, that is, there no "official 
product" of, C04, it is internally used by both the USNO, as the 
timescale maintained, distributed to, and used by GPS, and the IERS, to 
determine values published in Bulletin A and to determine leap-second 
values as published in Bulletin C. From what I can tell C04 is *the* 
'consensus' of LOD as a matter of practical common use.

# EARTH ORIENTATION PARAMETER (EOP) PRODUCT CENTER CENTER (PARIS 
OBSERVATORY) - INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE
# EOP (IERS) 20 C04 TIME SERIES  consistent with ITRF 2020 - sampled at 
0h UTC
https://hpiers.obspm.fr/iers/eop/eopc04_20/eopc04.1962-now

(This is the version distributed by the IERS. (There are other links at 
USNO and NIST, and possibly others, to the same information)

It is indeed very tricky business, but the good folks at the many 
contributing observatories and time laboratories together with many data 
processing centers have made landing an airplane within a few inches 
possible. How this is accomplished is a topic of a very long essay.

-Brooks