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Bill,
Compass, as I understand, is somewhat imprecise instrument.
(The one I have permits 1/2 degree in the best case,
but i am still considering buying a better one:-)

In the "thought experiment" I propose I assume that a
compass (and THUS dead reckoning) is available.

The question is : do we have means to improve on that
(or to check our dead reckoning) by CelNav
without a sextant.

I suppose the answer is "yes".

On Tue, 2 Nov 2004, Noyce, Bill wrote:

> As another way to use rising and setting of stars -- how about
> using the compass to identify the azimuth at which some circumpolar
> stars rise and set?  I suspect that could tell you your latitude
> with reasonable accuracy, even without a watch.  Even if you can
> only read the compass to a couple of degrees, I think the
> uncertainty in such a latitude will depend more on the uncertainty
> of refraction at the horizon.  For example, consider a star whose
> path just grazes the northern horizon -- that tells us our latitude
> without being very dependent on the azimuth measurement.
>
> With a watch, you can get latitude from the length of time a star
> far from the equator is above (or below) the horizon.  Perhaps you
> could also estimate when it's directly in line with the celestial
> pole, allowing you to measure some stars whose rise or set occurs
> during the day.
>         -- Bill
>

   

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