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Omar:

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?

Although one can not get exact numbers, I've verified some Mayan recorded
events such as conjunctions
from BC dates.

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

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.

Thanks, Michael



At 09:11 AM 11/27/04 -0200, you wrote:
>Hello,
>
>First, I know that this message may be out
>of scope on a navigation list, but this one
>seems to be very ecletic. So here is the
>problem:
>
>I'm trying to validate the results of
>a planet position algorithm for early
>dates. So I searched for the oldest
>Mars observations I could find.
>
>In the book "History of Astronomy",
>by Anton Pannekoek, I found a little
>table of times of Mars oppositions
>in the period between 1580 and 1604,
>which is reproduced below.
>
>The book is not very detailed about that
>table (which is quoted below).
>It is based in the observations by Tycho Brahe,
>and is very important to the history of astronomy,
>since it was used by Kepler to discover his
>fundamental planet laws.
>
>- Are the dates in Gregorian calendar ?
>( I know protestant countries were slow
>   to adopt the new calendar, by as much
>   as 100 years ).
>
>- What is the time zone he used
>( or how can I convert the times to UT )
>Any hint will be appreciated.
>
>Omar
>
>P.S. Mars Oppositions by T. Brahe
>18/11/1580 01:31
>28/12/1582 03:58
>30/01/1585 19:14
>06/03/1587 07:23
>14/05/1589 06:23
>08/06/1591 07:43
>25/08/1593 17:27
>31/10/1595 00:39
>13/12/1597 15:44
>18/01/1600 14:02
>20/02/1602 14:13
>28/03/1604 16:23

   

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