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I just wrote Alex off list, then decided to write on list to say:

Nice post Alex

On Nov 21, 2007, at 1:00 PM, Alexandre E Eremenko wrote:

>
>
> Dear Fred,
>
>> My only
>> quibble is that you might rephrase your conclusion to,
>> "I could not
>> get it to work."  Maybe a more skilled observer
>
> Yes, of course. 4 years ago, when I joined the list, one of
> the list members (I think it was George) wrote that he
> challenges anyone to determine his (modern, metal)
> sextant arc correction from
> stars. I tried to do this. I made several hundred observations
> of stars, and failed.
> My MOST PRECISE observations are in fact lunars
> (Sun-Moon, Venus-Moon and Jupiter-Moon).
> To determine arc correction from such lunars, one has
> to make observations for few weeks of good weather
> as the distance from the Moon to the body changes over the whole
> range of the scale.
> I did it. My results are in reasonable agreement with the
> arc correction determined by factory instruments (Freiberger
> and Cassens-Plath).
> So I can say that from such Lunars I can determine the
> arc correction with 0.1-0.2 accuracy, by several months
> of observations of Sun-Moon and Moon-Jupiter distances,
> and a lot of averaging.
>
> In principle ANY observation of known angles would give
> you the arc correction.
> I tried many other methods. But nothing else works in my
> conditions. For the artificial horizon I cannot find a stable
> enough platform. A dog running 100 feet away shakes
> the artificial horizon! Not mentioning cars and trucks.
> (Have not tried
> mercury yet:-)
> For the church-steeple
> method discussed on this list (which sounds
> very reasonable to me), I do not have enough church-steeples,
> and anyway do not have a 360 degree panorama from my observation
> place.
>
> Alex.
>
>
>
> >



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