NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Precision clock
From: Fred Hebard
Date: 2008 Jan 10, 15:51 -0500
From: Fred Hebard
Date: 2008 Jan 10, 15:51 -0500
If you can go digital, stop watches run continuously. On Jan 10, 2008, at 1:30 PM, Geoffrey Kolbe wrote: > > Thankyou for this Paul. I was hoping to get away from using > essentially two > clocks - a chronometer (WWV in your case) and what amounts to a > deck watch > (the stop watch). > > Stop watches usually have a maximum period over which they will run > as a > stop watch - usually about ten hours or so. So it is not possible > to start > a common stop watch at the top of the hour at midnight and let it > run on > for months more. > > Geoffrey Kolbe > >> Years ago when I computed satellite orbital elements from visual >> observations, I obtained UTC from from a digital stopwatch. I >> started at >> a known time by listening to WWV on a radio. Rather than the top of a >> minute, I started the watch on the 10th second of the minute. This >> allowed me to catch the rhythm of the seconds ticks, and hit the >> button >> at the instant of the tick, rather than reacting to the tick. (WWV >> omits >> the ticks at the 29th and 59th seconds, which makes this method >> harder >> to use at the top or bottom of a minute.) >> >> After starting the watch, I would then test for an accurate >> setting by >> hitting the "split" button (to temporarily freeze the display >> while the >> watch continued to run) on several ticks, checking for a near zero >> fractional seconds reading each time. With a bit of practice it's no >> great trick to hit the mark plus or minus .02 second. >> >> To time satellite observations, I used the split button and let the >> stopwatch memory save the times. It could hold up to 10, which was >> more >> than I ever needed. > > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---