Great--3 more things I might not normally even fuss about but since it's your first contribution to PyFITS I will be pedantic ;)

1: For tests, if they were motivated by some particular issue, I like to include a URL to the issue in the docstring on a separate line.  In this case, a URL to this pull request would suffice.  See some of the examples in this module and just copy that.

2: When opening a file use the `with` statement instead.  Most of the time it doesn't matter but sometimes, particularly on Windows, if you don't explicitly use the `with` statement or otherwise explicitly close the file, sometimes it doesn't automatically close on garbage collection quickly enough.

3: No spaces inside parens, ex. `np.all( data['V_mag'] == 0 )` -> `np.all(data['V_mag'] == 0)`

Make those changes and we'll be good to go.  Thanks!