Moon's vissibility on April 3, 786 B.C.

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<<I'm further confounded as to why you would maintain that 1st Nisan

of April 3, 786 B.C. was invisible. The New Moon in right ascension

occurred at 8:50 PM LMT on the evening of April 2nd and the New Moon

in longitude more than an hour before that. So if sunset was at

about 6:10 PM on the evening of April 3rd at Babylon and the Sun

would have been sufficiently depressed below the horizon about thrity

to thirty five minutes later for the Moon to be seen, that means the

Moon was about 22 hours old and had sufficient altitude to be seen. --

Ken Bowser.>>

 

The difference between ephemeris time and universal time, the so-

called delta-t, is not accurately known in 786 B.C., and depending on

the approximate algorithm used it may vary from 5h53m to 6h20m (ref.:

http://www.phys.uu.nl/~vgent/astro/deltatime.htm). With the Swiss

Ephemeris (swewin32.exe) based on DE406 one can calculate the

ephemeris time of the new moon in longitude on April 2nd: 22h32m51s

ET, which adding delta-t means that the geocentric new moon happened

sometime between about 16h13m and 16h40m GMT (=U.T.)

 

The coordinates of the Babylon archeological site are 32N30/44E22,

the local mean time of the new moon is then + 2h57m = from 19h10m to

19h37m. But since we are talking about naked-eye vissibility, the

calculation must be topocentric, which can be done easily with

swewin.exe. The topocentric new moon therefore happened in Babylon

sometime between 19h40m and 20h07m GMT, which at the Babylon site is

from 10:37 to 11:04 PM LMT.

 

Sunset at Babylon the next day (April 3rd) occurred at 6:10 P.M. LMT,

with the Moon 10.7 degrees away from the Sun and a vissibility of

0.8%. Its altitude above the horizon was 10,42'. The topocentric

position of the Moon at sunset that day (April 3rd) in the Fagan-

Bradley sidereal zodiac was 28,42 Aries. It set 55 minutes later,

when the Sun was 11 degrees below the horizon.

 

Conclusions?

 

Juan