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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.


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