.. _Astropy: http://astropy.org
.. _Skyfield: http://rhodesmill.org/skyfield/
.. _PyEphem: http://rhodesmill.org/pyephem/
.. _Numpy: http://www.numpy.org
.. _Matplotlib: http://www.matplotlib.org
.. _pytz: https://pypi.python.org/pypi/pytz/
.. _pytest-mpl: https://pypi.python.org/pypi/pytest-mpl
.. _Nose: https://nose.readthedocs.io
.. _WCSAxes: https://wcsaxes.readthedocs.io
.. _astroquery: https://astroquery.readthedocs.io