radio-astro-tools/spectral-cube — pull request #34 by astrofrog (2014-04-29 16:57:44+00:00)
Title: closest_spectral_channel error message can be confusing

This message:

```
raise u.UnitsError("{0} cannot be converted to {1} without a "
"rest frequency".format(value.unit, spectral_axis.unit))
```

is confusing if the user makes an error besides forgetting about rest frequency (e.g. providing a bad unit like seconds)