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IAUC number

                                                  Circular No. 5211
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505

(2060) CHIRON
     J. Luu, Harvard-Smithsonian Center for Astrophysics; and J.
Annis, University of Hawaii, report:  "We obtained JHK imaging of
Chiron on Mar. 7-8 UT with the University of Hawaii 2.2-m telescope
(+ 256x256 NICMOS array) in 0".7 seeing.  The images show Chiron to
have magnitude J = 15.22 and colors J-H = +0.26 +/- 0.04, H-K =
+0.08 +/- 0.04 inside a 3".0-diameter aperture.  Within the
uncertainties, these colors are consistent with solar colors (J-H =
+0.31, H-K = +0.06) and are the same as those determined before
activity. Preliminary analysis shows that Chiron has a very faint
extended coma in the infrared, with surface brightness 21 mag/arcsec2
at 2".5 from the nucleus.  These are believed to be the first
infrared images of the coma of Chiron."

     D. A. Leahy, University of Calgary, reports:  "Very Large Array
observations made 1986 Aug. 3 of 1E 1740.7-2942 (cf. IAUC 5032,
5140) show a weak 6-cm (about 1 mJy) and 20-cm (about 4 mJy) radio
source.  The radio source lies within the error circle of 1E 1740.7-
2942 and has a position determined to about 1" accuracy:  R.A. =
17h40m41s.82, Decl. = -29 41'39".0 (equinox 1950.0)."

     R. L. Baron and T. Owen, Institute for Astronomy, University of
Hawaii, communicate:  "We report the detection and imaging of
emission features at 3.4 microns (CVF) that are associated with the
poles of Jupiter.  These features appear as arcs of emission that
appear to correspond with a possible complete auroral oval.  Both
poles show similar emission and the north pole features have been
observed to rotate with the planet.  These observations were
obtained on Jan. 31.32 UT at the NASA Infrared Telescope located on
Mauna Kea, using ProtoCAM, the IRTF facility instrument.  Additional
observations took place on Feb. 1 and 4.  Several prominent H3+
lines have been identified within the 3.4-micron passband (R.
Joseph, private communication).  The bulk of the planet is quite
dark due to CH4 absorption at these wavelengths.  Significant limb
brightening is seen extending from the polar region to within tens
of degrees of the equator.  As in the 4-micron band (cf. IAUC 5132),
no comparable features were seen on Saturn."

1991 March 18                  (5211)             Daniel W. E. Green

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