Dear Frank,
I must read your reference...
> I have a little book ("A Manual of
> Modern Navigation" by S. M. Burton,
> 1941) with a chapter on the particular
> case of very high altitudes.
The more I think about this, the more snags
I see. If I am very close to the sub-solar
point, and I try sweeping the horizon, I am
sure I would find that bits of ship got in my
line of sight! With the sun zipping past the
zenith I would be bound to miss the critical
moment!
I must clearly think some more :-)
You add...
> On land I believe a theodolite can be used
> to give very accurate sun altitudes.
Ah. Here I do have a tiny bit of experience
and I hit another snag. Take a look at
http://www.surveyequipment.com/total-stations
You will see what modern instruments are like.
They all have handles across the top which stop
you looking close to the zenith.
Even with a lowish-altitude sun there are snags.
You can't (sensibly) look at the sun through the
telescope without suitable precautions which
require a special purchase. When you fix it all
up you then find that the bottom part of the unit
gets in the way. You can't get your eye near the
eyepiece.
Alas, I am definitely a theoretical navigator
and surveyor rather than a practical one!
Very best wishes
Frank
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