Hi Wolfgang
The watch you really want is a rattrapante watch.
Fundamentally, it is a double chronograph watch. Keep one set to your time zone and the other set to GMT. The interesting thing about the rattrapante is that you can 'freeze' one of the chronographs (I choose to freeze GMT). Once you have transfered the time from the frozen chronograph to your log, a touch of the same button brings the hands of the watch right back to CURRENT TIME. That is, although the hands of the frozen chronograph were not moving, the chronograph continued to accurately track time.
Whilst these watches are not cheap, they perform admirably. I have tracked mine vs the USNO master clock and have found it gains 0.100 seconds per day (one hundred milliseconds).
Best Regards
Brad
> Date: Wed, 16 Jun 2010 14:57:45 -0700
> From: cfuhb-acdgw@earthlink.net
> To: NavList@fer3.com
> Subject: [NavList] Re: timing of sights
>
> Wolfgang Hasper wrote:
> > Dear all,
> > many times I thought of a stopwatch that allows timing
> > a sight by just freezing the digital display by push
> > of a button, while, of course, the watch runs on.
> > Another push of the button should then reset the
> > displayed time to the actual moment...
>
> This is the "split" function, very common on digital stopwatches.
> When the stopwatch is running, you press a button to "photograph" the
> time and store it in a memory. The stopwatch keeps running and does not
> reset.
>
> The "lap" function is similar, except that the watch resets to zero.
> This allows you to time each lap of a race with a single watch. In the
> old days you did this with two mechanical stopwatches, one in each hand.
> When your car crossed the line, you started one watch and stopped the other.
>
> I think all modern digital stopwatches combine the split and lap
> functions. That is, each memory location stores both the split time and
> the lap time.
>
> My $25 Timex wristwatch has a stopwatch with split and lap functions,
> but you must select one or the other. It can't do both. Also, there's no
> memory. The display freezes for 10 seconds so you can read the split or
> lap time, then returns to normal.
>
> For celestial nav, a "stopclock" with a split function to store the
> Greenwich time and date would be better than a stopwatch, but I've never
> seen such a device, although many stopwatches display the date and time.
> So, you have to 1) start the watch at a known time before beginning the
> observations, or 2) start the watch at an arbitrary time, and determine
> the start time later.
>
> In either case, never stop the watch until you're satisfied with the
> observations. If you suspect a mistake in the stopwatch start time, it's
> easy to check -- if the watch is still running! Simply take a split on
> your time standard and re-compute the start time. But if you stop the
> watch, a check is impossible.
>
>
> > I wonder if this awfully expensive thing (~160$) would
> > at least offer what I was looking for?
>
> "Awfully expensive" is right. I think you can get a good stopwatch for
> about 1/3 or 1/4 of that price.
>
> --
>
>
>
>
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