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Subject: Re: Bubble horizon
From: Robert Eno (enoid@XXX.XXX)
Date: Tue Dec 17 2002 - 08:39:58 EST
Happy to respond. I find the results are more accurate if the size of the
bubble is slightly larger than the body being observed; in the case of the
sun or moon, the diameter of the bubble should be just enough to encircle
those bodies. In the case of stars and planets, it is a fine balance. If the
bubble is too small, I find that it becomes sluggish and lags, thus the
accuracy drops off. It should be lively enough to move freely with the
slightest movement of the observer. I am finding it hard to encapsulate this
in words. It is one of those things which one must experience first-hand in
order to fully grasp the concept.
Robert
----- Original Message -----
From: Dr. Geoffrey Kolbe <geof@XXX.XXX>
To: <NAVIGATION-L@XXX.XXX>
Sent: Tuesday, December 17, 2002 3:52 AM
Subject: Re: Bubble horizon
> Robert Eno wrote:
>
> >To make a long story short, unless you can adjust the size of the bubble,
> >you will experience errors; sometimes gross errors.
>
> I, and I am sure some others on the list, would be grateful to Robert if
he
> could make this short story a little longer. Why is the size of the bubble
> critical? Is Robert concerned that the damping of the bubble movement is a
> function of bubble size, or that the accuracy with which the celestial
> object can be centered in the bubble is a function of bubble size, or some
> other consideration?
>
> To answer George Huxtable's question on the sort of accuracy one should
> expect from a bubble sextant. I have a Link A-12 aircraft sextant (still
> available from Celestaire, last time I looked,) and I would expect an
> altitude measurement to be within +/- one minute. I am disappointed if I
am
> two minutes out and I cannot remember the last time I was more than two
> minutes out.
>
> Geoffrey Kolbe.
>
>
>
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