When I was observing at the Sierra Buttes last Thursday at a public
star party and last night of the SF State astronomy class, there was a
great shadow transit of Io (along the NEB) early in the evening. At
the same time, there was a transit of Callisto (further north but
initially at a similar longitude) and both the shadow of Io and
Callisto were both prominent. In fact, I assumed I was watching the
shadow of Callisto since it was so dark and sharply defined (several
people found Callisto more obvious than Io's shadow), but I realized
the next day using StarryNight Pro that Callisto's shadow transit did
not begin until after Jupiter had set. In general, when I've observed
satellite transits they often get lost by the time they transit
Jupiter's meridian, so I'm not sure what to make of the observation of
Callisto?
Steve Gottlieb
Received on Mon Jul 26 22:27:14 2004