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Thank you to all for interesting information in reply
to "Averaging". There is one point on which I think additional
comment is necessary:

On Thu, 7 Oct 2004, Ken Gebhart wrote:

> The idea of averaging sextant readings using a marine sextant,
> (ie. instead
> of using a bubble), really has no basis because acceleration
> has no effect
> on it.

The procedure of averaging observations using a marine sextant
is recommended by many books and manuals, from XVIII century
to these days.
It is not specific to bubble horizons or effects of acceleration.
It is also used on land.

The purpose of this procedure is to increase precision.
In fact this is a standard procedure increasing accuracy of
ANY scientific measurements.
The theoretical foundation of this procedure lies in
the "Method of Least Squares" by Gauss. The most
comprehensive discussion
in the context of practical astronomy
of this theoretical basis is contained in the last chapter of
Chauvenet's 2-nd volume.

The specific of aerial observations is that the random error
coming from acceleration is very large, and the averaging has
to be done quickly. That's why they have a built-in mechanism,
integrator, that does it automatically.

Alex.

   

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