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Again,

A one-day error would come close to 15 degrees.  It also would place
the objects at a different spot in the sky, changing refraction and
parallax, possibly accounting for the remaining difference from the
moon's rate of movement of about 13 degrees/day.  Do moon altitudes
accompany the lunar distances?  These would settle this question
quickly.

Fred



On Apr 23, 2004, at 11:30 AM, George Huxtable wrote:

> Ken Meldrew has been very inventive in speculating about different
> possible
> errors that might have been made in those Lewis and Clark lunars. And
> even
> considered a combination of two possible errors. I'm sure this is the
> right
> attitude to take. If there was an observational blunder that it was
> possible to make, you can be pretty sure that at one time or another
> L&C
> will have made it. There most be SOME explanation for that strange
> data-set
> of Dec 2-3 1803!
>
> His first speculation was that he had found the mystery star which had
> the
> right coordinates to correspond with the measured distances,
> supposedly to
> "Aldebaran". Already, we have established roughly how much out-of-line
> with
> the Moon's track (to one side or the other) a star would have to be so
> that
> the same star could possibly fit both sets of observations, A and C.
> And
> then, we have to search those two segments of sky for a star that's
> just
> the right distance from the Moon.
>
> Well, there's such a plethora of stars in the sky, that there must be
> many
> that will fill the bill, but the question is: is there a bright and
> prominent star, that could have been mistaken for Aldebaran? However,
> the
> only one Ken has been able to come up with so far is magnitude 4.5, and
> Frank Reed has pointed out that such a dim star could hardly have been
> seen
> in the sextant, let alone mistaken by Aldebaran, not even by L&C. I
> agree
> with that view, and now Kan Meldrum has acknowledged it too.
>
> Next Ken proposed that the sextant may somehow have been set to an
> angle
> exactly 15deg less than was intended. Then, as Frank has suggested,
> casting
> around the sky for a bright star at that wrong angle from the Moon,
> Betelgeuse would become the obvious candidate.
>
> But why should the sextant have been set to exactly 15deg in error for
> observation-set A? And then, set to some new value, for
> observation-set B,
> of "Regulus", which so far we have not considered in detail. And then
> set
> again exactly 15deg in error for observation-set C. This is not a
> single
> accidental error, it's a recurring error. What might cause the 15deg
> displacement?
>
> I thought that the answer might perhaps be found if, in error, the
> required
> angle had been set against the wrong end of the vernier scale, if that
> was
> just 15deg wide; an easy mistake to make. However, with a sextant
> divided
> to quarter-degrees, and a vernier reading to quarter-minutes, as this
> one
> seems to be, I presume that the vernier scale would be marked 0 to 15
> (minutes), but this would have to span a length on the main scale, not
> of 0
> to 15 (degrees) but 0 to 49 and three-quarters. Or perhaps 15 and a
> quarter; either should work. Can anyone, such as Henry Halboth, with an
> instrument calibrated to 15 arc-seconds to look at (which I don't have)
> check that this view is correct, please. If so, setting the degree
> scale at
> the wrong end of the vernier would give rise, not to a 15 degree
> error, but
> one that differs by from 15 degrees by all of 15 minutes. Quite enough
> to
> destroy that otherwise-attractive hypothesis, I'm afraid.
>
> So I am still unconvinced about the suggested scenario: that the
> sextant
> angle was set 15deg too small, on two separate occasions, and then
> Betelgeuse was substituted for Aldebaran. I can accept that the second
> might follow from the first, however. Can anyone offer further
> persuasion?
>
> However, I applaud the ingenuity that has been shown so far, by all
> concerned, and thank them for their continuing interest in what
> appears to
> be a fascinating, if intractable problem.
>
> Henry Halboth asks if it might be possible for the error in the lunars
> could result from measuring to the wrong limb of the Moon, and the
> answer
> is "no. it isn't possible". A limb blunder could give rise to an error
> in
> lunar distance of about 0.5 degrees, not much more. We are trying to
> explain an error of somewhat over 1deg, for obs. A, and well over 1deg
> for
> obs. C.
>
> 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.
> ================================================================
>

   

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