NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Latitude by Lunar Distance
From: Frank Reed CT
Date: 2006 Oct 12, 21:01 EDT
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From: Frank Reed CT
Date: 2006 Oct 12, 21:01 EDT
Hi Peter, you wrote:
"Sure; that's interesting enough Frank, if not necessarily accurate.
For example, I've been following this topic from 3 locations (with different 'IP
addresses') within Australia."
Yep, sure. I wouldn't be shocked if both of the Australian hits on that
"cones" page are yours. Most of the others have more detailed geographic
information (the four views from Spain are all over the country).
You also wrote:
You also wrote:
"Another matter of interest connected with this topic is the unanswered
comment:
'The correction for parallax is positive and that for refraction is
negative. There will be an infinite number of positions where the two
corrections can cancel one another, i.e.; the distances will be the
same.' "
'The correction for parallax is positive and that for refraction is
negative. There will be an infinite number of positions where the two
corrections can cancel one another, i.e.; the distances will be the
same.' "
Yes. There is an INFINITE number of points where the apparent distance will
have the same value as the value I measure, but they're not randomly scattered
about. Those points, infinite in number, are the points of the "cone of
position". They intersect the Earth in arcs which can be approximated locally by
"lines of position". Where two lines of position cross, that's your fix --one
point (to some level of accuracy). This is not so different from standard
celestial navigation. Every line of position consists of an infinite number of
points.
And you wrote:
"The method you propose seems to be ingenious: top marks for devising it and bringing it to our attention. But it doesn't seem to be very practical."
"The method you propose seems to be ingenious: top marks for devising it and bringing it to our attention. But it doesn't seem to be very practical."
Hey, you want practical, buy a GPS receiver! <g> Practical is
strictly relative when it comes to practicing celestial navigation in the year
2006. But let's be clear, the method I've described does work. Yes, it depends
on observations which will challenge your skill as an observer (we all like
that, right?) and test the quality of your sextant (nothing wrong with that
either). The results are accurate to +/-6 miles in the positional fix (less
accurate in one dimension as the Moon falls lower in the sky). Not great,
but it's a neat trick if you can't see a horizon or get a
level. Real celestial navigation without any horizon --real, artificial, or
implied.
And
"I'm only too happy to be proved wrong on this, but you have been
unresponsive in providing requested details from a number of posters. This would
seem to do you a disservice when it comes to stimulating further interest or
serious attention."
Hey if folks are interested, terrific. If not, 'non fa niente'. And,
Peter, if you're still missing some "details", just let me know.
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
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To post to this group, send email to NavList@fer3.com
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