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George wrote:
I use the formula-
D = arc cos[(cos d - sin s sin m) cos S cos M /(cos s cos m) +Sin S sin M]
and I get D= 85.7384º. This is the corrected lunar distance, that has to be
compared with prediction.

 

Jeremy replies:

 

I think this is the first time I've seen a LD formula without using Haversines, and am copying it so I can do these with my calculator. 

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George wrote:

 

This has to be compared with Jeremy's averaged chronometer time of 06h 22m
59s for his lunar distances. So my conclusion is that his chronometer was
slow by 1 minute 54 seconds. Or, perhaps more realistically, that his
chronometer was correct and his lunar-derived GMT was in error by 1 minute
54 seconds. That isn't a bad result, for a lunar. It would have put his
deduced longitudes out by about 28.5 arc-minutes, which would have (but only
just) qualified Jeremy for the Longitude Prize, if he had been observing
around 240 years ago. The total error in angle in the whole process was less
than an arc-minute, which for a first-shot at a lunar, is creditable work
indeed.

 

Jeremy replies:

George, you can tell parliament that I will take it all in sterling.  LOL.  Seriously though, this is officially my sixth lunar observation.  My first used the Starke tables when I bought them on a whim in 1999.  The next ones are the ones I posted on the list during the last few months.  Once I get a sextant here at home, I will try some land observations and see how I do with those.

 

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George says:
Changing height of eye will have little affect on a lunar, being no more
than a correction to a correction.

 

Jeremy replies: I see your point.

 

Jeremy