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

[Guest guest]

>Juan,

>So sorry, I should have said the visual _Moonset at 7:17 PM LMT.

>Is this agreeable to you?

>D*S

 

Using Riyal with ELP2000-85 adjusted to DE403/404, and the coordinate given

for Babylon, the center of the Moon crosses the horizon by oblique

ascension (or rather, descension) at 7:03:40 PM LMT.

 

using the swiss ephemerides with DE406 modern standard and a different

model of delta-t for comparison, there is a difference of 17'33 " in the

longitude of the Moon. When I introduce this difference as an empirical

correction to Riyal, I obtain a time 1.4 minutes before, or exactly 7:02:13

P.M. LMT.

 

Since the Moon's disk is about 34', this means that it disappears below the

horizon about 1.4 minutes after the times given. A *visual* moonset will

involve atmospheric refraction, which introduces a small time difference of

3 seconds only (7:02:16 in the DE406 calculation above).

 

Juan

[Guest guest]

>Juan,

>So sorry, I should have said the visual _Moonset at 7:17 PM LMT.

>Is this agreeable to you?

>D*S

 

Using Riyal with ELP2000-85 adjusted to DE403/404, and the coordinate given

for Babylon, the center of the Moon crosses the horizon by oblique

ascension (or rather, descension) at 7:03:40 PM LMT.

 

using the swiss ephemerides with DE406 modern standard and a different

model of delta-t for comparison, there is a difference of 17'33 " in the

longitude of the Moon. When I introduce this difference as an empirical

correction to Riyal, I obtain a time 1.4 minutes before, or exactly 7:02:13

P.M. LMT.

 

Since the Moon's disk is about 34', this means that it disappears below the

horizon about 1.4 minutes after the times given. A *visual* moonset will

involve atmospheric refraction, which introduces a small time difference of

3 seconds only (7:02:16 in the DE406 calculation above).

 

Juan