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The only problem I can see with this would be in high latitudes, since
the sunrise and sunset are both very drawn out (if they happen at
all).  I wonder if that one-degree-ish estimated accuracy holds in the
high 50's and 60's?

Here in Juneau (about 58* North), the sun slides along the horizon for
a while on either end of its arc, and it would be pretty hard to tell
when it first touches.  The long twilight might fool the light sensor
on the tag, too?

Nels


On Sun, 13 Feb 2005 18:28:18 -0800 (PST), Frank Reed
 wrote:
>
> Jared wrote:
> "It seemed interesting, that with just a watch and calendar
> one should be able to get latitude this way. Since most modern watches run
> to better than a second a day, this would seem to be a reasonable navigation
> tool."
>
> You can get longitude, too. If your watch is running well, as you travel
> east, sunrises and sunsets will occur at earlier and earlier watch times.
>
> This technique of navigation is actively employed on a small device that
> operates in an area inaccessible to GPS signals --underwater. Do you have
> $4200 to spare? Then you, too, can be the proud honor of a celestial
> navigating fish tag. I brought this up briefly on the list over a year ago.
> Here's a link to their web site and a description of the device:
> http://microwavetelemetry.com/Fish_PTTs/archival.php
>
> They get one-degree-ish estimated accuracy in latitude and longitude by
> timing sunrise and sunset (based on light levels corrected for depth, which
> is measured by pressure). This may be one of the last scientifically
> significant uses of celestial navigation. I guess it was easier than
> teaching the tuna to use sextants and H.O.229.
>
> "Has anyone seen a formula for this, or does anyone want to give it a try?"
>
> The easiest way to do it would be trial and error with the standard formulas
> for sunrise/sunset. Or with an almanac, just interpolate.
>
> -FER
> 42.0N 87.7W, or 41.4N 72.1W.
> www.HistoricalAtlas.com/lunars

   

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