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Bill,
I think the "rule of thumb" you are requesting was posted in
my previous
message. Several messages I read after that seem to
confirm it.
The rule is roughly the following: the averaging will
improve the precision of your result EXCEPT
in the following situation:
A body near the meridian AND on high altitude.
If the body is two compass points away from the meridian
everything is fine.
If a body is lower than 60d everything is also fine.

So in MOST cases of altitude measurement, the averaging
of the altitudes (over 5 min interval) is justified.
For the Lunar distances it is probably ALWAYS justified.

The rules for the altitudes
refer to the situation where the
expected
single measurement error is about 05' or more.

For those who care about 0.1' (say on land, with artificial
horizon etc.) the rules have to be modified: you have to
be further away from the meridian if the altitudes are high.

Alex.
On Thu, 21 Oct 2004, Bill wrote:

> My questions were, how much error from averaging is acceptable,
> and is there
> a rule of thumb for estimating how much error there will

   

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