NavList:

There was a vivid discussion in 18th century on the use of Galileo satellites (the 4 most bright satellites of Jupiter) in navigation. I can easily see them with my 8x40 binocular, and their periods are small enough to determine time. The smallest period (of Io) is 1.8 days, and then the next two  go in proportion 1:2:4. So an occultation of Io occurs roughly every day, and one does not even need a sextant to time it. I sort of remember seeing an old nautical almanach which contained the tables for them. One question is how accurately you can time an occultation. But one could use satellite-Juiter distances instead. These can be surely measured by a sextant within 0'1 or 0'.2, and making tables for them is a routine matter.

My question is: Do any old CelNav manuals discuss or include an instruction for using Jupiter satellites for longitude determination? It seems that the method has better accuracy than Lunars, and requires almost no calculations. Was this method ever really used at sea? And if not, why exactly?

I read somewhere that this was the most precise method for determination of longitude on land, before the advent of telegraph. There is also a substantial literature (scientific as well as fiction) about attempts to stabilize a platform on a ship for these observations. But I do not understand the need for a stabilized platform: cannot you use an ordinary binocular from a ship without any stablized platform?