Central Bureau for Astronomical Telegrams
IAUC 4684: 1988p; (2060)
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Read IAUC 4685
Circular No. 4684
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 1988p (SMM 6)
O. C. St. Cyr, NASA Goddard Space Flight Center, reports his
discovery of another comet during routine inspection of
coronagraph/polarimeter (C/P) images from the Solar Maximum Mission.
Measurements have again been made by A. Stanger, High Altitude
Observatory, and reduced by D. Pitone and B. Twambly at the SMM Flight
Dynamics Facility:
1988 UT R.A. (1950) Decl.
Nov. 18.17708 15 33 04 -19 52.8
18.24861 15 34 22 -19 36.6
18.25972 15 34 34 -19 34.8
SMM 6, estimated at mag +1, is perhaps the faintest comet
detected by C/P, although sporadic electronic artifacts in the raw
data have precluded other position measurements and a reliable
brightness estimate. These artifacts and the comet's faintness also
mean that the above positions are more uncertain than usual (accuracy
0.2 solar radii, 2 deg in p.a.). The comet's projected path on the
plane of the sky appeared to miss the occulting disk (radius 1.7 solar
radii). The object disappeared in a coronal streamer and was not
detected again. Nevertheless, computations by the undersigned show
that the above observations can be represented within 2' by the
orbital elements on IAUC 4668 for SMM 5 and T = 1988 Nov. 18.35 ET,
and the fit is within 1' with T = 1988 Nov. 18.36 ET and q changed
from 0.0053 to 0.0056 AU.
(2060) CHIRON
S. J. Bus and E. Bowell, Lowell Observatory; and L. M. French,
Air Force Geophysics Laboratory, report V-band CCD photometry of (2060)
Chiron on Oct. 31 and Nov. 1, carried out by Bus at the 0.91-m reflector
of the Cerro Tololo Interamerican Observatory. They estimate Chiron's
rotationally averaged magnitude as being 16.64 +/- 0.01 on Oct. 31,
indicating no further change in the object's absolute magnitude since
the observation reported by Cruikshank et al. (IAUC 4653). However,
Chiron was observed to brighten by 0.030 +/-0.005 mag from one night to
the next, only 0.005 mag of which could be ascribed to changing
geometry. Less than half the 5.9-hr lightcurve was sampled, but the
rotational phase was accurately enough known that comparison with
extensive observations made in 1986 could be made, with the result that
the difference between maximum and mean brightness appears to have
diminished from 0.044 to about 0.02 mag.
1988 December 3 (4684) Brian G. Marsden
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