Central Bureau for Astronomical Telegrams
IAUC 4945: JUPITER I (IO); 1989r
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Circular No. 4945
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
JUPITER I (IO)
M. E. Ressler and M. Shure, Institute for Astronomy (IfA),
University of Hawaii, report the first groundbased, resolved infrared
images of Io. The volcano Loki is easily seen as a point source against
Io's disk. The images were obtained during an engineering run at the
NASA Infrared Telescope Facility with ProtoCAM, the IRTF's 58 x 62 InSb
array camera. The observations were suggested by J. Spencer (IfA) and
J. Goguen (JPL). Images were obtained through the K, L and L' broadband
filters and through a circularly-variable filter at 3.40, 3.90, 4.08 and
4.80 microns. The plate scale was 0".13/pixel in seeing conditions of
0".4 on all nights. During 1989 Dec. 22.37-22.54 UT Io was followed
through 30 deg rotation, beginning with Loki approximately midway
between the eastern edge and the center of Io's disk and ending when
Loki was just west of center. Follow-up observations were made on Dec.
23.42, when Loki was on the far side of Io, to verify Io's image
diameter and to search for possible surface features. Additional images
were obtained on Dec. 24 while Loki was near the western edge of the
disk. Preliminary calculations show the FWHM of Io's disk to be
1".2-1".3 (in agreement with the known value of 1".2), the magnitude of
Loki to be L' roughly 6.3, and the integrated magnitude of Io (plus
Loki) to be L' roughly 3.0.
COMET OKAZAKI-LEVY-RUDENKO (1989r)
J. R. Ducati and C. M. Bevilaqua, Instituto de Fisica,
Universidade Federal do Rio Grande do Sul, Porto Alegre, report
photoelectric photometry of this object performed on eight nights
during 1989 Nov. 30-Dec. 23, with molecular filters and diaphragms of
50", 100", 150", 200" and 250" on the 0.50-m Cassegrain reflector at
Morro Santana Observatory. Ratios of intensities of molecular bands to
neighboring continua A = 484 and B = 684 (wavelengths in nm) are:
(C2 514)/A = 10.95 +/- 2.5 at the nuclear 50" region, increasing
slightly outwards; (C3 406)/A = 1.35 +/- 0.54 at the center, falling 50
percent outwards; (H2O+ 700)/B = 2.93 +/- 0.36 for the first four
nights, constant over the object; (H2O+ 700)/B = 5.87 +/- 1.66 for the
last four nights, falling 50 percent outwards; (CO+ 426)/A = 0.43 +/-
0.09 at the center, falling 40 percent outwards. In addition A/B = 2.2
+/- 0.43 for the first six nights and 5 +/- 1 for the last two nights,
increasing outwards.
Total visual magnitude estimates by A. Pearce, Scarborough, Western
Australia (0.20-m reflector): Jan. 3.56 UT, 9.7; 5.72, 10.0. There was
a tail 0.2 deg long in p.a. 48 deg on the second night.
1990 January 16 (4945) Brian G. Marsden
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