Hi Ann,
thanks for your feedback!
Yes, the first moon is Ganymede, then Io, (J), Callisto and Europa.
Well, I did not normalize the moons in brightness.
However, Europa has indeed the highest albedo of the four moons.
(Europa = 0.67, I = 0.63, G = 0.43, C = 0.22)
The egg-shaped spot is White Oval BA, which has a long history.
In the end of the 90ies, three smaller white ovals merged to form WO BA.
Those three ovals were observed since 1939!
So, the GRS is not the only long-lasting feature in Jupiter's atmosphere.
cheers
Mario