Central Bureau for Astronomical Telegrams
IAUC 6010: 1993e; 1986 DA
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Circular No. 6010
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)
For the Hubble Space Telescope (HST) observing team, K. S.
Noll and T. E. Smith, Space Telescope Science Institute, report:
"HST observations on May 17.65 UT confirm the presence of an object
between nuclei G (= 15) and F (= 16), as reported previously by
Jewitt and Trentham (IAUC 5999). The HST WF image clearly shows an
extended object located 4".20 east and 4".18 north of nucleus G.
On May 17, the peak pixel of the new object is 39 times fainter
than the peak pixel of nucleus G. The ratio of summed pixels in a
0".5 x 0".5 box, centered on nucleus G and the fainter new object,
is 25 (3.5 magnitudes). The magnitude of nucleus G in this same
aperture is R = 21.62 +/- 0.05. HST PC images taken on Mar. 29.00
also show a faint object northeast of nucleus G. The object is
extended and appears in each of the four exposures. The object is
centered 1".85 east and 3".63 north of nucleus G. The ratio of the
peak pixel in nucleus G to the peak pixel in this object is 24 and
the ratio in a 0".5 x 0".5 box is 27. The brightness of nucleus G
was constant between the Mar. 29 and May 17 images to within a few
percent. The search for other objects near the limit of
detectability has not been completed."
1986 DA
M. J. S. Belton, National Optical Astronomy Observatories,
writes: "1986 DA was determined to be an M-type near-earth minor
planet and was studied in detail by radar and optical techniques
during its only apparition. Thought to be a fragment of a
differentiated asteroidal core, 1986 DA is easily reachable by
spacecraft with small launch vehicles; it is therefore an important
target for certain NASA Discovery missions that are currently being
planned. However, the orbit is somewhat uncertain and requires new
observations for orbit improvement to a level that would make it an
acceptable target. 1986 DA will be at opposition in late Nov. 1994
at mag 20, passing through a phase angle of only 0o.14 on Nov. 23.6
UT. I should appreciate receiving early notification of any
observations that are made at this opposition, since this would
strengthen the case for 1986 DA as a target for a space mission.
An ephemeris can be found in the Catalogue of High-Precision Orbits
of Unnumbered Minor Planets 1994 (see MPC 23363)."
1994 June 24 (6010) Daniel W. E. Green
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