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Alex,
Again, I agree with your comments.  I was referring to using an averaging
mechanism to accomplish the task.  Averaging mechanisms have their own
accuracy specifications of up to four minutes of arc, which is added to the
accuracy of the sextant itself.  Thus accuracy of the entire system is
worse. Certainly manual averaging of many individual sights by the navigator
himself would improve overall results
Ken
----- Original Message -----
From: "Alexandre Eremenko" 
To: 
Sent: Friday, October 08, 2004 9:06 AM
Subject: Re: averaging devices on sextants


> 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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