NavList:

   

Reply

Michael

> I'd like to hear what you learn about these observations.  I've adapted
the
> AA routines by Mosier from JPL
> to produce an almanac and I'd also like to know how it performs for early
> dates.  Maybe we could compare results?

I would be pleased. I'm moving to a new address
and  my books are all in boxes. But I expect to
resume the historical astronomy studies soon.

> If you come up with a JDate for these or other observations, let me know.

I got a reply from Mr Gingrich, which I quote below.
In it, he mentions a book by Meeus (which I haven't seen)
that has all the mars opposions in years 0 to 3000.

> For what it's worth I calculate the difference in RA between the Sun and
> Mars to be 180 degrees some time
> between 06:28:04 and 06:28:05 UT on Nov 18 1580 JDate UT 2298474.76949,
TDT
> 2298474.77059 dT=95.397.

As G. Huxtable noted,  Brahe of course worked
with the apparent positions of Mars and Sun
( he was not aware that light has a finite speed,
 nor of the size of the orbits ).

The DT is a problem value to me. I found that J. Meeus
Astronomical Algorithms DT methods are diverging
from true values after just 20 years of the book
publication.  How did you calculate the DT ?

Omar

P.S. Message from the amateur astronomy newsgroup:
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Pannekoek's table appears to employ the Julian calendar. The first
opposition listed, for the year 1580, was the only one that occurred
before the Gregorian reform was implemented in Catholic countries.

The times shown are for a time zone 10 hours *ahead* of UT (GMT).
Subtracting 10 hours from each entry (being sure to roll back the
date by one if the result is less than zero) will give you the UT
Julian calendar dates/times.

Incidentally, Jean Meeus lists every Mars opposition for the years
0 - 3000 in his book _Astronomical Tables of the Sun, Moon, and Planets_
(second edition), 1995, pp. 62 - 96.

Mark Gingrich - San Leandro, California
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

   

Reply