Central Bureau for Astronomical Telegrams
IAUC 4884: 1989x
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Circular No. 4884
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
COMET 1989x (SMM 10)
O. C. St. Cyr, High Altitude Observatory, reports his discovery
of the tenth probable sungrazing comet recorded by the coronagraph on
the Solar Maximum Mission. The following measurements were made by J.
Burkepile and A. Stanger, High Altitude Observatory, and the reduction
was by D. Pitone and B. Twambly of the SMM Flight Dynamics Facility at
NASA Goddard Space Flight Center. The measurements refer to the
'head' (i.e., the sunward end of the bright cometary tail), and radial
distance and p.a. are believed accurate to +/- 0.1 solar radius and
+/- 0.1 deg, respectively.
1989 UT R.A. (1950) Decl.
Sept.28.696 12 13.31 - 2 10.3
28.713 12 13.91 - 2 10.3
28.724 12 14.35 - 2 09.2
28.760 12 15.76 - 2 06.8
28.771 12 16.12 - 2 06.6
28.776 12 16.34 - 2 05.9
28.788 12 16.90 - 2 05.0
SMM 10 is one of the brighter SMM comets, and in comparison to
the others it has a large tail (longer than a solar diameter). As was
the case with SMM 5 (IAUC 4668) the tail has an unusual shape, with a
conspicuous bulge on the northern side (i.e., toward the solar equator)
near the end. Also like SMM 5, there appears to be a wispy structure
extending further north and sunward from this bulge, and the wispy
structure appears to track with the comet in at least three images.
SMM 10 was probably brighter than mag -4, and the head disappeared
into the occulting disk after Sept. 28.792 UT. The comet was not seen
to reappear, but the data stream was interrupted during Sept.
28.85-29.02 UT. The following parabolic orbital elements, derived by
B. G. Marsden, Center for Astrophysics, on the assumption that the
perihelion direction is that of the Kreutz sungrazers, satisfy all the
above positions within 1'.2: T = 1989 Sept. 28.855 ET, Peri. = 87.50,
Node = 8.94, Incl. = 144.76 (equinox 1950.0), q = 0.00476 AU. The
assumption that the comet's original orbit is the same as that of
comet 1963 V (Marsden 1989, A.J., in press) yields a slight systematic
trend with residuals up to 1'.7 and the elements: T = 1989 Sept.
28.857 ET, Peri. = 87.25, Node = 8.52, Incl. = 144.58 (equinox
1950.0), q = 0.00487 AU.
1989 October 25 (4884) Daniel W. E. Green
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