STS-78 Reentry Observed

Jim Varney (jvarney@mail2.quiknet.com)
Sun, 7 Jul 1996 06:40:33 -0700

Woke up at 4:25 AM local time to prepare for the observation of the reentry 
of Columbia.  First items of business was to turn on the television and hope
that the local cable company had NASA TV on (they use NASA TV as 'filler' to
plug gaps in their schedule on the least-watched channel), get camera and
binoculars ready, and fire up the coffee pot.  The last item is the most
important at 4:25 AM!  Anyway, heard the NASA TV commentator say that 
the deorbit burn was underway, so that told me I needed to be on my way.

Drove about a mile to an empty field that gave a relatively unobstructed
view of the horizon.  To the east the glow of the impending sunrise lit
up a beautiful profile of the Sierra Nevada mountains, with Venus being
softly filtered by a lone thin cloud.

Panic set in at about 12:09 UT.  Could not get the video camera to focus
distant homes and streetlights.  Checked the focus, lighting settings,
zoom settings, all to no avail... checked my watch... more panic... oops,
finder was cocked halfway up, so camera not pointing in the direction I
thought it was... grumble, need more coffee.

At last a rose-colored "star" appeared above the distant rooftops at maybe
4 degrees above the horizon, and it was rising fast.  Appeared slightly
north of west, which surprised me, as STS-77's reentry was south of west.
Put my 10x50 binoculars on the shuttle and the ion trail was easily visible
despite low elevation and growing dawn twilight.

For STS-77, NASA's predicted reentry sighting profile was way off.  Let's
see how they did this time:

  Predicted:                           Alt  Dir     Az      Sun Alt  Boom
  Sacramento, CA       12:14:45 UTC    76.2  S    (180.0)    -5.6    4:00

  Observed:
  Sacramento, CA       12:14:20 UTC    85    N    (  0.0)    -5.6    3:58

This prediction is actually better than this indicates, as I was positioned
about 10 miles south of downtown Sacramento.

Ion trail visible to the naked eye, but did not persist as it was lost in
the twilight.  I realize now that my previous magnitude estimate for STS-77
was too conservative; at culmination the shuttle had to have been mag -8
or better.  Venus and Jupiter were absolutely no match, and I wouldn't
argue if you said it outdid the moon.

Near culmination I quit filming and switched to binoculars.  The apparent
size of the fireball was 10-15 minutes of arc, with a serrated edge to the
brilliant pink glow.  Did I resolve the fireball itself?

Sonic boom was a little louder than STS-77 but still not a window-buster.
It was not a single boom, more like two booms blended together: ba-boom.
I had the good fortune of being at Edwards AFB for the landing of STS-1:
the double sonic boom there was a definite eardrum-smasher.  So, was not
surprised the sonic boom had this non-singular quality to it.  The double
boom, as I understand it, is caused by the shuttle's creation of two
supersonic shock waves, one from the nose and one from the tail.
When the boom hit some birds nearby went into a frenzy.  Probably thought 
the sky was falling.

Was able to follow Columbia into the brightening sunrise with binoculars 
down to an altitude of about 3 degrees.

Not the amazing spectacle that the dark-sky STS-77 reentry was, but still
a very nice sight.  Well, I've rambled on enough, and it's time for
breakfast.

  -- Jim



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Jim Varney      |  121^ 23' 54" W,  38^ 27' 28" N   |           Sacramento, CA
Member, SeeSat-L|            Elev. 31 ft.           |jvarney@mail2.quiknet.com
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