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I have been using the python ephem package for ephemeris and it is
based on code from Xephem, with a discussion of accuracy here
http://www.clearskyinstitute.com/xephem/

I have seen other discussions of accuracy of ephemeris software on
NavList and I am sorry if this has been covered before

1) Where can I find an analysis of the effect of errors on the
intercept  method? Hence the answer to the question "How accurate does
ephemeris need to be for celestial navigation?" . I know we are
limited by time and angular resolution in taking sights but we can
average over a series of sights to reduce this error, but after errors
in reading the sextant and chronometer is the next biggest error going
to be variations in the atmosphere? Suppose we are using celestial
navigation at a fixed point on land and we can average over different
atmospheric conditions.

2) Is there a "gold standard" ephemeris used in astronomy? It strikes
me in meteorology the gold standard must be to check predictions with
observations. Presumably there are observatories making high precision
measurements with minimal errors (for example when objects are near
the zenith to reduce refractions).

--
Professor of Applied Mathematics
University of Manchester
http://www.maths.manchester.ac.uk/bl

   

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