[IAUC] IAUC 8869: P/2007 R3; C/2007 N3 [25139-2008/05-R1]

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                                                  Circular No. 8869
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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COMET P/2007 R3 (GIBBS)
     A. R. Gibbs reports his discovery of another comet on
unfiltered CCD images obtained with the 1.5-m reflector in the
course of the Mt. Lemmon Survey ("discovery" observation tabulated
below); the four co-added 30-s frames show a well-condensed 8" coma
and a faint, narrow tail 20" long in p.a. 240 deg, while four co-
added 80-s frames taken around Sept. 14.37 UT show a condensed 11"
coma and a faint 30" tapered tail in p.a. 240 deg.  Four co-added
30-s exposures by Gibbs on Sept. 15.24-15.27 show a condensed 8"
coma and a faint 10" tail in p.a. 225 deg, while four co-added 80-s
frames taken around Sept. 15.35-15.36 show a condensed 10" coma and
a narrow 40" tail in p.a. 245 deg.  Following posting on the Minor
Planet Center's 'NEOCP' webpage, numerous other CCD astrometric
observers have also commented on the object's cometary appearance.
G. Hug (Scranton, KS, 0.30-m reflector) writes that the object
appeared diffuse on his images from Sept. 15.3.  J. G. Ries
(McDonald Observatory 0.76-m reflector) notes that her images from
Sept. 15.4 show a coma and a faint tail approximately 23" long
toward the southwest.  V. Gonano, E. Guido, and G. Sostero
(Remanzacco, Italy, 0.45-m reflector) report that fourth co-added
60-s exposures taken around Sept. 16.0 show a diffuse coma nearly
15" in diameter with a broad tail nearly 25" long in p.a. 260 deg.
P. Birtwhistle (Great Shefford, Berkshire, England, 0.40-m f/6
reflector) writes that his images from Sept. 16.0 show a 10" coma
with a 30" tail in p.a. 240 deg.

     2007 UT             R.A. (2000) Decl.       Mag.
     Sept.14.29338    0 41 55.38   + 1 26 12.0   18.9

The available astrometry, the following preliminary elliptical
orbital elements, and an ephemeris appear on MPEC 2007-S02.

     T = 2007 June  6.477 TT          Peri. = 292.699
     e = 0.53777                      Node  =  33.711   2000.0
     q = 2.20125 AU                   Incl. =   3.165
       a =  4.76219 AU     n = 0.094840     P =  10.4 years


COMET C/2007 N3 (LULIN)
     The following revised parabolic orbital elements for this comet
(cf. IAUC 8857) are from MPEC 2007-R56:  T = 2009 Jan. 10.7452 TT,
q = 1.211903 AU, Peri. = 136.8430 deg, Node = 338.4873 deg, i =
178.3716 deg (equinox 2000.0).

                      (C) Copyright 2007 CBAT
2007 September 16              (8869)            Daniel W. E. Green