QUESTION:
[Editor's Note: This question is based on Jim Taylor's Field Journal
from 2/27/97]

The above is all very (extremely) interesting (Like all the 
things your team writes and organize), however no mention is made 
if this is a symmetrical problem i.e. if there was data 
loss 6 minutes before and also after the occultation. That 
means the ^total^ data loss was 12 minutes.
This information is very critical for any explanation.
(You emphasize earlier, implying assymmetrical)
 
Can you give me the calculation what the minumum time 
should have been i.e. COS (declination) * diameter of 
jupiter / speed of Galileo.
   diameter of jupiter = 143800 km
The factor COS (declination) represents the hight above the 
equator (ecliptic?) of Jupiter. (Maximum dec = 0, Minumum dec = 90)

This information is also important. When Galileo is lower 
above the equator as predicted, ^total^ time of occultation 
will be longer as "expected".
 
ANSWER from Jim FH Taylor on April 8, 1997:
I will start out by saying that we eventually found the
cause of the 6-minute-early ingress.  It was an error in the ingress time
in a file used to generate the human-readable "space flight operations
schedule" (SFOS) that virtually everyone on the flight team uses.  The SFOS
showed ingress 6 minutes later than it actually occurred.  The egress time
was in error by the same amount.  The SFOS showed egress 6 minutes later
than it actually occurred.  Once I had determined these facts and made sure
that the times of the next occultation will be more thoroughly checked, I
had to go on to other things.

Why didn't I mention these errors in the Journal page you read?  After all,
the answer was known before the Journal was "published" in "Online".
Well, I didn't know it by end of day on February 27, when I wrote the
Journal.  I wanted the Journal to reflect our *best state of knowledge* at
the time it was written.  At that time, I only knew about the early
ingress.  We were not expecting to receive telemetry data immediately at
egress.  So I had no informatioin about egresss comparable to the lost
telemetry frame at ingress. The radio science man, Randy Herrera, told me
in our telephone conversation that he thought the egress had occurred early
also; he also said that he has seen early ingress at other occultations,
though not by such an extreme amount. I included paraphrases of his
speculations at the end of Journal.  We both knew there could simply be an
error which, in fact, was the cause.

Randy Herrera gave me an equatorial radius of 71492 km, including the
oblateness, and defined at the 1 "bar" atmospheric pressure level.

>This information is also important. When Galileo is lower 
>above the equator as predicted, ^total^ time of occultation 
>will be longer as "expected".

I understand what you're trying to get at.  However, I want to get home
tonight, so I'll merely provide you one assumption and some trajectory
data, and let you make the calculation.

Randy Herrera told me that this occultation was nearly equatorial.  Just
assume that everything (Jupiter, earth, and the spacecraft orbit around
Jupiter) are in a plane.  The trajectory data I see is included in a weekly
status report.  For the period February 6 - March 13, I extracted the
values, as follows.  The Jupiter radio occultation occurred from 20:17 UTC
on February 26 to  09:53 UTC February 27.  These are ground receive times
for the downlink, and they include the 6-minute correction!

February 6, 1997
     Distance from Earth        912,537,600 km (6.1 AU)
     Distance from Sun          770,169,800 km (5.2 AU)
     Speed WRT Jupiter          8,700 km per hour
     Distance from Jupiter      5,111,100 km (71.5 RJ)

February 13, 1997
     Distance from Earth        905,741,700 km (6.1 AU)
     Distance from Sun          767,982,500 km (5.1 AU)
     Speed WRT Jupiter          15,700 km per hour
     Distance from Jupiter      4,031,500 km (56.4 RJ)

February 20, 1997
     Distance from Earth        896,554,700 km (6.0 AU)
     Distance from Sun          765,175,000 km (5.1 AU)
     Speed WRT Jupiter          64,900 km per hour
     Distance from Jupiter      689,500 km (9.6 RJ)

February 27, 1997
     Distance from Earth        893,471,100 km (6.0 AU)
     Distance from Sun          769,610,000 km (5.1 AU)
     Speed WRT Jupiter          18,000 km per hour
     Distance from Jupiter      4,157,300 km (58.2 RJ)

March  6, 1997
     Distance from Earth        885,616,700 km (5.9 AU)
     Distance from Sun          770,466,400 km (5.2 AU)
     Speed WRT Jupiter          9,800 km per hour
     Distance from Jupiter      5,833,100 km (81.6 RJ)

March  13, 1997
     Distance from Earth        875,194,600 km (5.9 AU)
     Distance from Sun          770,038,300 km (5.2 AU)
     Speed WRT Jupiter          6,900 km per hour
     Distance from Jupiter      6,375,900 km (89.2 RJ)