astropy/astropy — pull request #1200 by keflavich (2013-06-20 17:51:11+00:00)
Title: Spectral equivalencies for optical, radio, relativistic conventions

Implemented the equivalencies listed in the added docs in https://github.com/astropy/astropy/pull/1176. Examples included in the docstrings. Fairly simple, but this PR is a crucial prerequisite for specutils.