NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Latitude by Lunar Distance
From: George Huxtable
Date: 2006 Nov 11, 16:25 -0000
From: George Huxtable
Date: 2006 Nov 11, 16:25 -0000
Frank Reed wrote-
...did YOU ever realize that you could determine a true
| position fix using lunar distances without any horizon at all? I
think it's
| quite a novel concept for this group of people.
Yes, I agree, it was an interesting notion, well worth bringing to our
attention. A notion which is NOT devalued by the fact that it was
first thought of nearly a century before; a fact which was also worth
bringing to our attention. Whether that notion was practical or
useful, then or now, is another matter. It was somewhat tarnished by
Frank's rather extravagant claims made about its precision "to six
miles".
But Frank is being over-sensitive when he writes-
I suppose that's why a couple of
| people were determined to attack it instead of trying it out.
I recognise myself as one of those couple, and wonder what Frank
expects to get when he presents such a notion to our list. What he
will get will be scrutiny, if this list is doing its job. Any such
proposal will be unpicked and examined for holes and flaws. If it
passes that test without serious defects coming to light, it's an
indication (but nothing more than that) that perhaps the idea is
indeed valid. This list acts an an almost-instant peer review, for
which I have been truly grateful when it has found flaws in my own
arguments; a more frequent occurrence than I wish to recall. We are
not a mutual admiration society, and thank goodness for that.
Finally, Frank has been asked to explain a procedure for deducing
observer's position from two Moon-star distances, quoting numbers.
Even a contrived, fictitious example would be worthwhile. That would
allow us to understand where his predicted celestial positions are to
come from (for example), how resulting position-lines are to be
plotted, how an overall error-budget can be estimated, and whether his
estimate of a result to six miles is at all reasonable. Is it
necessary to presume an approximate observer's position beforehand? I
still look forward to seeing how the job is to be done.
George
contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
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