A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Iwancio
Date: 2021 Jan 6, 11:14 -0800
Just want to point out something that tripped me up earlier. The limit is "less than 0.9 s," not "less than or equal to." Radio time signals aren't able to communicate DUT values (official estimates of UT1-UTC rounded to the nearest 0.1 s) greater than 0.8 s. For example, the system of double-ticks used on WWV, WWVH and CHU is only used on seconds --:--:01 through --:--:16, and can only communicate DUT values of -0.8 s through +0.8 s inclusive
There are currently two sets of double-ticks in the above-mentioned shortwave sginals, occuring on --:--:09 and --:--:10, indicating UT1 is currently behind UTC by about 0.2 s.
(It will apparently remain at -0.2 s until COVID-19 lockdowns end and an office intern is able to go outside and poke at the earth's hairspring with a stick.)