A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2018 Sep 28, 06:30 -0700
...given this fairly optimistic CN model, we need less than one second probable clock error over 30 days. Can a quartz wristwatch get there? Barely. The best ones can. Because of aging, the watch must have some recent rate characterization; if you wait more than a year or so, aging will cause its rate to drift too far, by an unknown and poorly predictable amount...
Does this mean if I buy a quartz watch on a flee market (which I always do) - it has already aged-in to a more horizontal/predictable curve? I'm watching the going of a Timex I recently bought there - after I changed the cell there it settled-in and now it barely gains more than a second a week. The age of the watch must be several years by now.
UT1 is predictable to ~10 ms accuracy 30 days in the future, so that's not a problem at all. Maybe it was slightly pedantic to mention it.
By the way, the RWM right now transmits the dUT1 value of +0.06sec.