Central Bureau for Astronomical Telegrams
IAUC 9086: C/2009 U3
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Circular No. 9086
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://www.cfa.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
COMET C/2009 U3 (HILL)
R. E. Hill reports his discovery of a comet (discovery
observation tabulated below) on CCD images taken in 3"-4" seeing
with the Catalina 0.68-m Schmidt telescope, noting the object in
co-added exposures to have an nuclear condensation of diameter
about 5"-7" elongated southwest-northeast, with a coma of diameter
about 12"-15", and a diffuse tail about 15"-20" long in p.a. 220-
230 deg. A similar appearance was noted by Hill on four co-added
60-s exposures from Oct. 22.4 UT in slightly better seeing, noting
a nuclear condensation of diameter about 10"-15" and "no noticeable
coma", with the broad, diffuse tail being about 20" long in p.a.
220 deg. After posting on the 'NEOCP' webpage, other CCD
astrometrists have also commented on the object's cometary
appearance. G. Sostero, E. Guido, and P. Camilleri (fifteen co-
added unfiltered 60-s exposures obtained remotely with a 0.35-m
reflector at the Skylive-Grove Creek Observatory near Trunkey,
Australia; Oct. 21.7) report a diffuse coma about 10" in diameter
with a central condensation and a tail about 12" long toward the
west; their further co-added frames on Oct. 22.6 also show a
diffuse coma of size about 12". Exposures taken by A. Asami and N.
Hashimoto (Bisei Spaceguard Center 1.0-m reflector; Oct. 21.74-
21.76) show a 15" coma with a tail 25" long in p.a. 235 deg. P. R.
Holvorcem notes that three co-added 120-s exposures taken by M.
Schwartz and himself on Oct. 22.4 with the Tenagra II 0.81-m
telescope near Nogales, AZ, USA, show a coma diameter of 9" with a
5" tail toward p.a. 195 deg. A. D. Grauer (Mt. Lemmon 1.5-m
reflector, Oct. 22.4) reported that his co-added 60-s exposures
show a 9" coma and a flared tail 15" long in p.a. 230 deg. H. Sato
(Tokyo, Japan, remotely using a 0.25-m reflector at the RAS
Observatory near Mayhill, NM, U.S.A., on Oct. 22.5) finds a diffuse
coma of diameter 15". R. Miles writes that four stacked 15-s
frames taken by G. Privett with the 2.0-m 'Faulkes Telescope North'
at Haleakala on Oct. 22.6 show the comet to be elongated 5".0 x
1".5, aligned in p.a. 75-255 deg.
2009 UT R.A. (2000) Decl. Mag. Observer
Oct. 21.32407 3 50 08.41 +14 50 23.7 17.6 Hill
Additional astrometry, the following parabolic orbital elements,
and an ephemeris appear on MPEC 2009-U67:
T = 2010 Mar. 11.739 TT Peri. = 83.676
Node = 48.951 2000.0
q = 1.22986 AU Incl. = 49.134
(C) Copyright 2009 CBAT
2009 October 22 (9086) Daniel W. E. Green
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