It's really cool, but I'm not particularly fond of the Flash Plugin that they've used. It's a little bit slugish, and IMHO something like Google/Bing/Leaflet could provide a much better user experience.
That said, here's what I'll do: I'll get a smaller image from ESO, split it in tile images and display it on Leaflet.
To split the image I'm going to use an utility called GDAL2Tiles. I'll show two variants of this:
- using the command-line tool
- using a Graphical Interface called MapTiler