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Doug,

Just as a matter of note, assuming that the terrain was not flat, would
you not agree that following your position on 7.5'-series topographic
maps, with terrestrial cross bearings as needed would have been
sufficient to locate you within 0.1' of your position?  I.E., that the
celestial nav was more for the exercise than for finding out where you
were.

Fred

On Feb 22, 2005, at 3:27 PM, Royer, Doug wrote:

> Doug:
>
> On Tue, 22 Feb 2005, Royer, Doug wrote:
>
>> I made a flat,triangular reflective A.H.
>> out of dark plexiglass last year.
>> It has 2 bubble levels( $ 3.50 each)
>
> What is the accuracy of this A. H. ?
>
> A
>
> Alex,
> It was good enough to give me positions within 2 mi. of a gps pos while
> travelling in Indian country(while going cross-country).
> It's near impossible to keep an accurate dr while travelling
> cross-country.When sights were attempted 1st I had to take cross
> bearings
> from terrestial landmarks,convert the mag bearings to grid
> bearings,plot the
> pos on the projection to find the eastings and northings coordinates
> that I
> was going to use as my sighting position. 2nd set up the gear to shoot
> and
> then take sights when available. There is just to many variables in
> all this
> when doing it "real time" in less than idea conditions(terrain,weather
> and
> state of fatigue).
> If I had to have relied on only sight reduced positions,map work and
> bearings we would have been close enough at the end of the trip(20
> days)to
> be less than a day's hike/ride from where we were to be picked up.
> So as for accuracy..........accurate enough to get us where we needed
> to
> be.Sorry,I can't be more specific than that.
> The flat A.H.  and an Astra IIIB sextant is what I used(along with a
> Palm OS
> based sight reduction program) on the entire trip.
>

   

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