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I would like to have the ecliptic coordinates of a point on Earth. I can set up an observer using Pyephem:

station = ephem.Observer()
station.lon = '14:18:40.7'
station.lat = '48:19:14.0'
station.pressure = 0
station.epoch = ephem.J2000
station.elevation = 100.0

Then setup a date

station.date = ephem.date(datetime.utcnow())

But I don't know how to get this point coordinates in the Ecliptic system. If I try the Ecliptic function on the station Object it fails. Is there a way to do that in PyEphem?

nixx
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1 Answers1

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If by “the ecliptic coordinates of a point on Earth” you mean “the ecliptic latitude and longitude which are overhead for a point on Earth,” then you might be able to generate a correct position by asking for the RA and declination of the point in the sky directly overhead for the location — where “directly overhead” is expressed astronomically as “at 90° altitude in the sky.” You would follow your code above with something like:

ra, dec = station.radec_of('0', '90')
ec = ephem.Ecliptic(ra, dec)
print 'Ecliptic latitude:', ec.lat
print 'Ecliptic longitude:', ec.lon

Try this technique out and see whether it returns a value anything like what you are expecting!

Brandon Rhodes
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  • Thanks for the answer Brandon. I'm not sure I was clear enough. I want to draw the path during time - for example one year - of a point that is at the surface of the Earth at a specific latitude and longitude. I would prefer to have this data in ecliptic coordinates, is your solution working for that? – nixx Aug 24 '16 at 11:37
  • Yes, my solution will work fine for that! You can call `station.date = ...` over and over again for as many times as you want, and then for each time use my code to ask about the ecliptic latitude and longitude. Your drawing will be very busy — a place on the Earth’s surface draws a circle around the celestial sphere every 24 hours! – Brandon Rhodes Aug 24 '16 at 19:16