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I've been asking Henry Halboth where his lunar distance tables, to be used
as he suggests for emergency navigation, were to come from, and he tells us-

"As respects tables of Lunar Distances, I have been using beautifully posted
tables at http://www.math.uu.nl/people/wepster/tables.html which have been
well put together and can be printed off for a number of years, as well as
for any particular voyage time frame."

Good for him. I think that preprinting those tables, to cover an intended
voyage, would indeed fulfil his intended purpose, being just like the tables
in the old almanacs.

I wonder if he recognises their author, as Steven Wepster, about whom I
wrote in Navlist posting 3216, just three days ago. He will be receiving his
doctorate for his lunar researches in Utrecht on Tuesday, as long as he
succeeds in defending his thesis against an examination in public.

Henry added-

" I see little use to the so called approximate methods of clearing the
distance. I find a pure trigonometrical solution, espescially by use of the
haversine formula, to be more understandable and certainly with fewer
corrections - I have yet to test the difference in accuracy as between
5-place and 6-place logarithms and have not been able to locate any 6-place
natural haversine tables. "

I would welcome more detail from Henry about his use of that method.

I presume that his recent spot-on lunar was taken from on land. Is that
correct? Could he then see a good horizon, beneath the azimuth of each of
the two bodies, for taking the altitudes? How much does he think his lunar
distances might be degraded, if they are taken from a smallish boat, such as
a sailboat or a lifeboat, in a moderate sea?

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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