NavList:

   

Reply

Marcel Tschudin wrote-
| I would have assumed that the information on the eclipses would
| provide information on both, deltaT and nutation. May be someone who
| has the article on how deltaT was evaluated can be more precise.
| Geoffrey?

I haven't been following this "Star of Bethlehem" business, but the most
respected workers in this field of understanding past delta-T have, for some
years, been Morrison and Stevenson, and I attach a definitive paper on the
topic from 2004. It gives several other references. I can't help with more
recent references than that one.

Marcel doesn't need to worry about the effects of nutation, which are
cyclic, so never build up to more than a fraction of a minute. The tilt of
the Earth's axis with respect to the ecliptic, however, decreases
progressively by about 8 arc-minutes per millennium, in a way that's very
precisely calculable.

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.

--~--~---------~--~----~------------~-------~--~----~
Navigation List archive: www.fer3.com/arc
To post, email NavList@fer3.com
To , email NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---

File:

  

   

Reply