Python coordinate conversions, following convention of several popular Matlab routines.

a few quick examples:

from pymap3d.coordconv3d import *

lat,lon,alt = eci2geodetic(eci,t)
az,el,range = geodetic2aer(lat,lon,alt,42,-82,0)

Popular mapping toolbox functions ported to Python include:

aer2ecef  aer2enu  aer2geodetic  aer2ned
 ecef2aer  ecef2enu  ecef2enuv  ecef2geodetic  ecef2ned  ecef2nedv  ecef2eci
 eci2ecef
 enu2aer  enu2ecef  enu2ecefv  enu2geodetic
 geodetic2aer  geodetic2ecef  geodetic2enu  geodetic2ned
 ned2aer  ned2ecef  ned2ecefv  ned2geodetic
 vreckon

for converting right ascension and declination to azimuth and elevation, please see the function radec2azel

or simply use the functionality of AstroPy 1.0+ to do radec->azel conversion

python setup.py develop

Atmospheric effects neglected in all functions not invoking AstroPy. Planetary perturbations and nutation etc. not fully considered.

Consider using python-geopy as well. For example, if you're seeking Vicenty distance.