Central Bureau for Astronomical Telegrams
IAUC 5892: 1993e
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Circular No. 5892
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@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
PERIODIC COMET SHOEMAKER-LEVY 9 (1993e)
J. V. Scotti and T. Metcalfe, Lunar and Planetary Laboratory,
have provided accurate absolute astrometry for nine of the nuclei of
this comet from CCD images obtained with the 0.91-m Spacewatch
telescope at Kitt Peak generally on nine nights during Mar. 30-July
19. The observations and the orbits determined from them by the
undersigned are being published in the Nov. 29 batch of Minor Planet
Circulars. The nuclei involved are those numbered 1, 5, 6, 7, 11, 12,
14, 15 and 17 by Jewitt et al. (1993, Bull. Am. Astron. Soc. 25,
1042), and the orbit for the brightest nucleus (nucelus 7) is as follows:
Epoch = 1994 May 8.0 TT
T = 1994 Apr. 1.3226 TT Peri. = 355.1307
e = 0.206613 Node = 220.9658 2000.0
q = 5.382476 AU Incl. = 5.7864
a = 6.784178 AU n = 0.0557774 P = 17.670 years
It must be emphasized that these computations were made for the
various nuclei independently. All the orbits agree in giving a minimum
distance of 0.0008 AU from the center of Jupiter on 1992 July 8.0 UT
(cf. IAUC 5800), but the computed sky-plane positions of the nuclei at that
time understandably differ (by up to 12" in R.A. and 16" in Decl.,
with the poorly observed nucleus 6 showing a shift of up to 70" in
Decl.)--although the orbits placed nuclei 5, 11 and 17 then within a
region only 1".2 times 1".7. Nevertheless, the close agreement of the
ephemerides extrapolated back to the beginning of 1992, and even to
the previous perijove 0.06 AU from Jupiter in July 1989 (with the
indication that there were several earlier revolutions around Jupiter),
clearly demonstrates that the basic break-up occurred very close to the
1992 perijove and involved very small velocity differences.
The new computations indicate that the 1992 prediscovery
ephemeris on IAUC 5801 requires adjustment as follows: Feb. 8, by
-1.13 time min in R.A., by -12.6 arcmin in Decl.; Mar. 9, -0.81, -9.7;
Apr. 8, -0.51, -6.5. G. Tancredi, University of Montevideo; and M.
Lindgren and C.-I. Lagerkvist, Uppsala University, report that 90-min
Kodak IIIa-J exposures of the region in Mar. 1992 with the 1.0-m
Schmidt telescope at the European Southern Observatory and tracked at
the motion of Jupiter showed no trace of the comet. On 1992 Mar. 6
the limiting magnitude for a stationary object was B = 22.1 (or B =
21.3 for an object having the comet's motion).
1993 November 22 (5892) Brian G. Marsden
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