[Kstars-devel] Elevation correction for rising/setting times

[Pablo de Vicente]

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El Miércoles 3 de Septiembre de 2003 13:50, Jason Harris escribió:
> Hi Pablo,

Hello Jason,

>
> I'm a bit worried that the Moon's correction has the opposite sign of
> everything else.

 Yes, it puzzled me also.

>
> (1) It looks like we are not applying the correction for the Moon's
> Angular size, as we do for the Sun:
>
> Sun:  correction = -34 (refract) + -16 (angular radius) = -50
> Moon: correction = -34 (refract) + 0.7275*P (parallax) = +0.125
>
> (2) The moon's coordinates already include a correction for parallax (a.

 Argh.., I did not notice this. You have already mentioned that in previous 
emails but I forgot...

> k.a. "figure of the Earth").  Are we correcting for it unnecessarily?

  Then yes, this correction is unnecessary. I think it is reasonable we use 
the same correction as the Sun, but I would like to check it somewhere else. 

  I have an almanac and I have checked the rise/transit/set time for Madrid. 
but  I have to refine the rise/set/transit code because, though it works fine 
for the Sun it does not work correctly for the moon. It seems it needs one 
more iteration.

  The OAN almanac says that the Moon rises at 13:31, and sets at 22:52 in 
Madrid. KStars says that it rises at 15:27 and sets 00:34 if I use the same 
correction as with the Sun, and this time changes if I change the time. 
However if you set the time and see the Moon appear/disappear above/below the 
horizon in KStars's main window, the moon rises at  15:31:30 and sets at 
22:51:40 which differs about 30 seconds from the almanac values. This 
difference is aceptable taking into account the almanac only gives the value 
with a precission of minutes.

  I need to revise the code for the rise/transit/set times and once corrected 
check if applying the same correction as for the sun (-50 arcmin) works fine.  

regards,

Pablo.
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