Save downloaded skymaps?

[martinjohndyer]

Since the issue raised in #36 we now force the download of the skymap for each event, but we actually don't store them anywhere (they will go to a temporary location based on astropy.utils.data.download_file). Perhaps it would be useful to download and store the skymaps for future reference, for instance #37 could use that.

Cross ref to https://github.com/GOTO-OBS/goto-obsdb/issues/53, which includes suggestions for storing event details in the ObsDB. Based on today's technicon with the file transfer from La Palma to Warwick we could store a hash of the skymap in the database for a quick lookup to see if the file has changed for #37, but I'd still say keeping the skymaps stored somewhere would be handy (actually we also store raw VOEvent XMLs already, which is arguably less useful).

[martinjohndyer]

Skymaps are saved in the alert database as of #71.