astropy/astropy — pull request #2371 by eteq (2014-04-25 18:06:07+00:00)
Title: Add small angle equivalency

This adds a `small_angle_distance` equivalency for the commonly-used approximation that transverse distance ~ d_LOS * angle in radians. Of course, the "right" way to do this is with `coordinates`, but sometimes you want the quick-and-dirty conversion like this.