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Gary LaPook had suggested that these pages-

http://articles.adsabs.harvard.edu//full/1919PA.....27..359W/0000359.000.html
http://articles.adsabs.harvard.edu//full/1919PA.....27..359W/0000363.000.html

would be of interest in showing what could be achieved in measuring
longitude-around-noon from equal-altitude observations of the Sun. However,
I hadn't understood the point he was making. He answers-

"Well I was impressed by the level of accuracy they achieved since it
is much better than the 5 nm level of accuracy that has been discussed
lately using sun sights around the time of noon."

Ah! Now I follow, and fully agree with Gary. But really, it shouldn't be a
surprise. It simply shows the precision that's obtainable when observations
are taken at well-separated times, so that the Sun has very different
azimuths, in the traditional way that mariners have always done such a job.
And highlights the sacrifice in accuracy that results from trying to confine
those observations to a short interval around noon. The contrast is
instructive.

George.

contact George Huxtable, at  george@hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.


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