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Herbert,
What you are saying seems to contradict
recommendations of many authors, including
"Complete on board Celestial navigator"
(p. 15 and 103).
Could you give precise references on the papers
which discuss non-linearity?

(My own crude estimates show that for altitudes up to 60d
and observations spread over the interval of 5 min,
the error introduced by the averaging is probably not more
than 0.3'. But I do not have a "complete theory" ready for posting:-)

On Sat Oct 09 2004 - 19:18:32 EDT Herbert Prinz wrote:

>Since both methods, the time sight as well as the lunar
>distance have
>fallen into total oblivion, manual averaging is a thing of the past.

>Before I address the idea of rejecting spurious data,
> let me clearify
>the terminology.

On Sun, 17 Oct 2004, Alexandre Eremenko wrote:

> There are two separate related phenomena here.
>
> 1. Aurora Polaris, the lights in the sky.
> They occur quite frequently and not necessarily
> very close to the poles.
> (The average number in New York is 10 per year).
> The zone of highest frequency (about 100 per year)
> in Northern hemisphere
> spreads to N Lat 57d over Canada).
>
> 2. Magnetic storms. They occur at the same time all over the earth.
> (This has nothing to do with polar regions).
> The compass deviation during such a storm can be up to several
> degrees and the storms last from few hours to several
> days. They may also interfer with radio transmission, and some
> say, even with electric power transmission.
>
> Apparently there is a relation between both phenomena,
> and they are caused by charged particles coming from the Sun
> and interfering with the Earth magnetic field.
>
> I do not know of any specific directions for navigators how
> to deal with magnetic storms, except the general recommendation
> of Russian manuals to determine compass correction by
> astronomical observations every day (usually by sunrise and sunset).
>
> Alex.
>
>
> On Sun, 17 Oct 2004, Lisa Fiene wrote:
>
> > The northern and southern auroras occur when electrically charged
> > particles from the sun interact with our earth's magnetic field.
> >
> > Just a question, if one were to sail in these latitudes during these
> > episodes of increased solar activity & the subsequent auroras these
> > would create, would it affect the ship's compass at all?
> >
> > I've always considered this a likelihood, however never having sailed to
> > these high lats, have never been able to test it.
> >
> > If it is the case, how do/did sailing vessels allow for this in their
> > navigation?
> >
> > Thanks, Lisa
> >
>

   

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