Central Bureau for Astronomical Telegrams
IAUC 3640: Prob. SUNGRAZING COMET
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Read IAUC 3641
Circular No. 3640
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
PROBABLE SUNGRAZING COMET
Images of a probable comet have been found at the Naval
Research Laboratory, Washington, on coronagraph exposures obtained
from the satellite P78-1 in 1979. The object was found by R.
Howard as a result of instrumentation developed and operated by
N. Koomen and D. J. Michels. The following heliocentric separations
rho (in units of the instantaneous solar radius) and position
angles theta (measured counterclockwise from the sun's north pole) have
been derived by N. Sheeley and converted to R.A. and Decl. by the
undersigned. The head of the object was somewhat brighter than Venus,
and a tail was directed roughly away from the center of the sun.
1979 UT rho theta R.A. (1950) Decl.
Aug. 30.789 5.96 234.2 10 26.47 + 8 45.1
30.796 5.67 233.8 10 26.80 + 8 45.5
30.802 5.27 234.3 10 27.22 + 8 47.8
30.809 5.16 234.6 10 27.36 + 8 48.6
30.816 5.09 235.4 10 27.43 + 8 49.8
30.856 3.65 235.7 10 29.07 + 8 54.8
30.867 3.11 236.1 10 29.67 + 8 56.9
30.885 2.56 239.2 10 30.28 + 9 00.7
At the last observation the object's head was at the edge of the
coronagraph's occulting disk. On the next exposure, taken at Aug.
30.989 UT, the tail is still present, and during the next several
hours cometary material evidently diffused around to p.a. ~ 360o.
The comet's orbit cannot be unequivocally determined, but
computations by the undersigned suggest that a retrograde solution is
to be preferred, for this better explains the previous failure to
detect the comet in a twilit sky. Other possible coronagraphic or
hitherto unreported visual detections of the object would of course
be very useful. Retrograde orbit solutions show some resemblance
to the orbits of the members of the Kreutz sungrazing comet group;
there would seem to be a good chance that the comet hit the sun
(for the head was not detected after perihelion). The following
possible orbital solution has been selected solely because of its
general resemblance to the Kreutz-type orbits:
T = 1979 Aug. 30.92 ET Peri. = 83.42
Node = 9.81 1950.0
q = 0.001 AU (assumed) Incl. = 142.42
1981 September 23 (3640) Brian G. Marsden
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