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Andres Ruiz has sent part of the text from an article-

Advancing Celestial Circles of Position
THOMAS R. METCALF
Institute for Astronomy, University of Hawaii

ABSTRACT
This paper presents rigorous equations, useful with computer reduction
of celestial sights, which correct the Greenwich Hour Angle and
declination of a celestial body for the motion of a vessel. Advancing
a circle of position in this way maintains the relationship between
the geographical position of the body and the vessel, and hence is the
best method for advancing an observation.

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Unfortunately, Andres' extract peters out just at the end of the first
paragraph of his section "Method", just when things get interesting.
And because there's no reference to the source of that article, I
can't follow it up further.

But I am suspicious that Metcalf, like many others, has got things
wrong. One worrying aspect is that he seems to be taking as an example
a body near the zenith, at about 85 degrees altitude, where dragging a
circle across the Earth's surface does indeed provide a good
approximation. But until we can read more of that paper, to see what
he is actually claiming, we will never know.

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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