adds New Cross Index module

[dreamalligator]

For Issue #39.

[tritium21]

Might want to adjust travis.yml so that it will install unittest2

[brandon-rhodes]

I have good news! I have finally come up with an idiom that I like for supporting star catalogs: using a Pandas dataframe to hold all the thousands or tens of thousands of stars. It provides easy looking and filtering for users, and integrates easily into the Star object.

To update this pull request now that Skyfield knows how star catalogs should work, check out the new routine that loads Hipparcos stars:

python-skyfield/skyfield/data/hipparcos.py

Line 44 in 5ff82b0

def load_dataframe(fobj, compression='gzip'):

Simply adapt this New Cross code to the same pattern and this pull request will be ready to merge. (Or, if it's been too long and you're on to other projects, just let me know and we can mark this as ready for other contributors to jump in and help with.)

Thanks!

[brandon-rhodes]

Since this has gone so long without activity, I am going to close it for now, but I am open at any time to seeing it re-open and seeing a New Cross Index loading routine added that creates a Pandas dataframe using the patterns in skyfield.hipparcos.load_dataframe(). I think it will be a nice addition to Skyfield.

Thanks again for your interest in Skyfield!

[dreamalligator]

yes this has been so long without activity, thanks for closing for now :)