PyEphem Rise/Set Azimuths for Stars and Constellations

Question

I can't seem to figure out how to calculate an azimuth of a star, let's say Sirius, when it is at alt=0 (star rise/star set).

So essentially in the end I will have two values.

Sirius.az @ star rise Sirius.az @ star set

Is this possible?

THANKS!

Answer 1

Simply check the .az attribute of the star once your observer object has determined the moment of rising or setting. For example:

import ephem

s = ephem.star('Sirius')

boston = ephem.Observer()
boston.lat = '42.37'
boston.lon = '-71.03'

boston.next_rising(s)
print s.alt, s.az
boston.next_setting(s)
print s.alt, s.az

Running this script at this moment gives me the encouraging output:

0:00:00.0 112:23:25.2
0:00:00.0 247:36:34.9

As you can see, the rising and setting routines have already established the moment of zero altitude, leaving the azimuth for you to read off and use!