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IAUC 6119: JUPITER; (253)

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                                                  Circular No. 6119
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
Phone 617-495-7244/7440/7444     TWX 710-320-6842 ASTROGRAM CAM

     F. Billebaud, Space Science Department, ESA-ESTEC, Noordwijk;
P. Merlin, F. Sibille, and I. Vauglin, Equipe Infrarouge,
Observatoire de Lyon; and P. Drossart and E. Lellouch, DESPA,
Observatoire de Paris, report:  "We have observed Jupiter on Dec.
18 and 19 with the 10-micron array camera 'C10mu' and its Circular
Variable Filter (CVF; spectral resolution 50) at the Canada-France-
Hawaii telescope on Mauna Kea.  We have recorded images at several
CVF wavelengths, in particular 7.81 and 7.93 microns.  The images
recorded at those two wavelengths exhibit a lower flux on a belt at
the latitude of the impact sites of comet 1993e, compared to all
other latitudes.  Although not homogeneous, the belt seems to cover
all longitudes, and the extension in latitude seems to be on the
order of 20o.  Preliminary processing of the images indicates that
the flux is about 40 percent lower at 7.81 microns and 30 percent
lower at 7.93 microns, when compared to the flux at near-equatorial
regions.  This corresponds roughly to a contrast of 7 K at 7.81
microns and 5 K at 7.93 microns; these two wavelengths probe the
methane emissions in the mid-stratosphere (>/about 30 mbar at 7.93
microns, and somewhat higher at 7.81 microns).  We suggest that
this atmospheric cooling in the impact regions may have two origins:
(1) cooling by efficient infrared radiators (NH3, HCN, H2O, etc.)
injected in the stratosphere during the impact period; (2) thermal
cooling of the haze and reflection of sunlight to space."
     Visual observations of Jupiter in poor seeing by D. Gray
(Durham, England, 0.4-m telescope; via J. Rogers) on Dec. 14-16 and
by D. H. Levy (Tucson, AZ, 0.20-m reflector) on Dec. 18.58 UT suggest
that the dark impact band is still very obvious, similar to its
appearance in September.

     D. W. Dunham, Applied Physics Laboratory, Johns Hopkins
University, communicates:  "In June 1997 the trajectory of NASA's
Near Earth Asteroid Rendezvous (NEAR) spacecraft will pass near
(253) Mathilde, a dark (albedo about 0.04) minor planet with
aphelion in the outer part of the main belt.  The NEAR Project is
considering observing this object during this flyby opportunity.
Lightcurve and spectroscopic observations of it are therefore
requested during the current apparition and should be e-mailed to
L.-A. McFadden (mcfadden@astro.umd.edu).  An ephemeris around
opposition (1995 Feb. 24) is given in EMP 1995 (see also MPEC 1994-
Y04).  Data far from opposition are also needed in order to attempt
a crude pole determination, and an extended ephemeris will be
supplied upon request to David_Dunham@jhuapl.edu."

1994 December 23               (6119)            Daniel W. E. Green

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