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I wrote earlier:
"By the way, have you ever considered the general problem of taking a series
of Sun sights in relatively rapid succession (at an arbitrary time of day,
not necessarily around noon)? For example, suppose it's 1500 local time. If
I take ten sights over half an hour, what kind of position fix can I get?
This is a generalization of the "sights around noon" problem. There's no
easy graphical solution but it's similar in other respects. "

And Andres, regarding your own software, you wrote:
"I have tested it with a simulator and the solutions are good solving for
position, and for position & motion. With real sights: ten taken over 40 min
aboard a sailboat, 3/5 Kt, the solution for position is really good, but it
isn't when including motion, I think because the course and speed were not
constant during the time of shooting the Sun. Is it very difficult to
maintain a constant motion when sailing. Aboard a motor vessel, freighter,
..., th thinks maybe go well, but I don't know..."

Yes, that's just what I was talking about. I know some people who use
another software package that implements this same math. Two of them have
told me independently that they find it amazing how efficiently this
"rapid-fire fix" can be generated: you shoot a bunch of Sun sights in a row
over a fairly short period of time, 30 to 40 minutes maybe, and you get your
position with surprising accuracy. And much like the noon situation I've
been describing, the positional accuracy perpendicular to the Sun's azimuth
is something like five times lower than the positional accuracy in the
direction of the Sun's azimuth. This is very similar to the lat/lon around
noon fix, except of course that for sights away from noon it probably
requires software to make it happen. I'm not aware of any easy graphical
trick that would work away from noon, and I would guess that none exists.

 -FER
PS: one of my service providers had a meltdown today, so if this message
turns up duplicated, I apologize in advance.



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