FIRST COMETARY IMPACT ONTO JUPITER OBSERVED AT CALAR ALTO OBSERVATORY 

A time sequence of four frames showing the impact of fragment A of
Comet Shoemaker-Levy 9 into Jupiter. The upper left frame shows
Jupiter just before impact. The bright object to the right is the
closest Galilean satellite Io, and the fainter oval structure in the
southern hemisphere is the Great Red Spot. The polar caps appear
bright at the wavelength of the observations, 2.3 um, which was
selected to maximize contrast between the fireball and the jovian
atmosphere.  The small dark spots on Jupiter are artifacts from Io in
these simple differenced images. In the second frame (exp. time 2s x
5), taken from Spain at UT 20:17:10 on July 16, the fireball appears
above the southeast (lower left) limb of the planet. The fireball
flared to maximum brightness within a few minutes, at which time its
flux surpassed that of Io.  The third frame (UT 20:21:23) was taken
near this maximum, and therefore has a shorter exposure time and was
stretched differently; this frame should not be used for quantitative
comparisons. By UT 20:42:04 (fourth frame), the impact zone had faded
significantly, although it remained visible for the three hours that
we were able to observe Jupiter.  The fireball was fainter at 1.7um
and not directly visible at 1.5um. Further monitoring suggests that
the bright zone may be rotating slower than the cloud deck on Jupiter,
possibly implying that the fireball is high in jovian atmosphere. The
bright spot remained visible for at least three hours, by which time
Jupiter was too low to permit further observations.  These images were
taken at the German-Spanish 3.5 meter telescope on Calar Alto in
southern Spain, using the near infrared camera developed by the
Max-Planck-Institut fuer Astronomie in Heidelberg, Germany.


Members of the Calar Alto observing team:

Max Planck Institut fuer Astronomie (Heidelberg, Germany)
  Tom Herbst
  Kurt Birkle
  Ulrich Thiele 

Max Planck Institut fuer Kernphysik (Heidelberg, Germany)
  Doug Hamilton

Universitaets-Sternwarte Muenchen (Muenchen, Germany)
  Hermann Boehnhardt
  Alex Fiedler
  Karl-Heinz Mantel

Instituto de Astrofisica de Andalucia (CSIC Granada, Spain)
  Jose Luis Ortiz

Astrophysical Institute Arcetri (Florence, Italy)
  Giovanni Calamai
  Andrea Richichi