At 04:03 PM 6/9/01 -0400, you wrote:
>Reply to : Laren (Larry) Dart
>
>>> I'd be interested in hearing of any pre-1620 eclipse observations in
>which locations are _solidly_known_, and how they compare when using both
>Guide's default dT and mine as given above. <<
>
>There are a whole host of ancient eclipse records / maps / formulae
>for delta-T in Historical Eclipses and Earth's Rotation by Stephenson.
>What is your particular interest in ancient eclipses ?
>
I'm aware of Stephenson's work, but haven't seen his book. I'm sure the
Lick library has it, but the trip to UCSC campus is a bit much for me now.
Guess I'll have to buy a copy if it's still available, but I imagine it's
pretty expensive.
I'm looking for ancient solar eclipses which were observed and recorded at
sites which are very definitely known, but which did not happen according
to modern theory. Example: there was an eclipse at Babylon in 136 B.C. but
the closest I can pin down the location of Babylon is "near" el Hillah,
Iraq. "Near" won't cut it. And also, was it observed in Babylon itself, or
"somewhere" in Babylonia? Exact locations are the hardest part! (Does
Stephenson's book have them?)
I'm working forward in time, starting with an eclipse observed in Anyang,
China, on June 5, 1302 B.C. The tentative equation I gave shows it as
total, astronomy programs show it with a magnitude of about 0.5-0.6.
The "whole host" of records and dT formulae you refer to are what keep me
trying to find something better. We may have to use tweaked algorithms for
practical work, but stringing two or three quadratic equations end-to-end
is hardly science. And when you get right down to the origins of delta T,
it's nothing more than an o-c residual. The hypothetical explanation that
it's caused by the slowing rotation of Earth may be so, or it may not.
Sorry for the slow response, Richard. I'm trying to get stuff together on
the Anyang eclipse, will put up a pointer in a couple of days to see if
there is any interest here. And, just for the record, my interest lies
strictly in astronomy, not astrology or biblical archaeology. ;->
Laren
--
http://www.got.net/~ldart