QUESTION:
How much time elapsed between the two sets of Neptune pictures (the two 
Hubble orbits). Was the expected rotation of Neptune reflected in the two 
images?.  Did the clouds rotate more or less than that?

ANSWER from Heidi Hammel on April 30, 1996:
There was an eight-hour time lapse between the starts of the
two sets of pictures (the two orbits).  This is just about half
of the expected rotation period at the latitudes we see most
easily in the pictures.  In other words, we got pretty much a 
"front view" and a "back view" (where front just means one half
and back means the other half).  
 
That is not enough to really measure cloud motions accurately,
because the only clouds you might even expect to see repeat
8 hours later would have been way far on the edge of the planet
in the first orbit, and then way far on the other edge of the
planet in the other orbit.  Just as we showed the a dark spot
near the north is very hard to detect (remember the basketball!),
clouds on the very edges of the planet are also very hard to detect
and measure.  So our LHST images alone will not be sufficient to
give us new information about rotation periods of Neptune's clouds.