NavList:

   

Reply

Thanks to Mike Burkes for his contribution to the discussion about lunars,
as follows-

>HI folks. From George's campsite location of 50 mi south of St Louis, I
>determined assumed position of 37 58.7 N,(George's Lat computation) 90
>25.3 W from Atlas.
>Aldebaran Hc: 67 16.3
>Moon       Hc: 26 10.0
>Cleared Dist : 60 44.7
>Lunar GMT   : 04-56-28 VIA Bruce Stark's Method
> I can show work either on or off List for interested parties. Please
>reply when able and show how off I am!

First, I think there's a problem when he says "90 25.3 W from Atlas." Does
this indeed come from the Atlas, or is it the final result of a longitude
calculation? If it's a calculated long, it's a much closer answer to the
expected value than I obtained, and it would be good to discover why.

On the other hand, if that longitude was taken from the Atlas, it's too far
West for the Miss., at that lat. It would put the expedition about 20 miles
inland, West of the Miss. I think this misunderstanding may be the result
of my own sloppy wording, when I described that camp as being 50 miles
South of St. Louis. I was just trying to give a notion of its general
geography, 50 miles or so downstream of St. Louis, which is what I should
have said. I wonder if Mike has taken my description literally, and drawn a
line South from St. Louis, for 50 miles. If so, it's entirely my fault.

In fact, modern mapping shows that the expedition must have been slightly
East of the 90deg W line, at 89deg 57.2'W, though L&C weren't to know that,
of course.

However, the initial longitude that's chosen should make no difference to
the final result. The lunar distance method is intended to discover the
true longitude, after all, even if it doesn't do so very accurately.

The computed altitudes I find for the Moon and for Aldebaran differ
somewhat from those that Mike quotes. Any such discrepancy is of great
interest, because I am trying to hunt down any error in my own calculation,
which if it exists may occur anywhere. I ask Mike to supply further
details, please; particularly of the GMT, on 3 Dec 1803, that he used to
obtain Hc for the Moon and for Aldebaran.

George.

================================================================
contact George Huxtable by email at george@huxtable.u-net.com, by phone at
01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
================================================================

   

Reply