Dealing with corrupt FITS files

[Tom Barclay]

ctrl+c when downloading a file from MAST results in a corrupted FITS file. Fix this!
Either force redownload a corrupted file or atomize the initial download.

[Dan Foreman-Mackey]

I switched to atomic writes so this should be better. If you already have corrupted FITS files you can force the overwrite with the clobber keyword argument.