Here is the page from his observing journal, but if you can't read that, see the translation here.
Pretty amazing what he was able to accomplish with that little telescope he made. I wonder if it performs better than the modern "Galileo" telescopes you can buy at Wallmart? Turn around and leave the store if you see these scopes!
Four centuries later, we go from his sketches and scribbled notes to actually "being there".
Here is a video by Dr. Paul Schenk from Io image data. Nice "Star Wars" effect, reminds me of the Millenium Falcon blasting it's way out of Mos Eisley!