[IAUC] IAUC 8837: C/2007 JA_21; P/2007 H1 [25139-2008/05-R1]

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                                                  Circular No. 8837
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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COMET C/2007 JA_21 (LINEAR)
     An apparently asteroidal object reported by the LINEAR survey
(discovery observation posted below; prematurely announced as 2007
JA_21 on MPEC 2007-J52) has been found by several observers to show
cometary appearance following posting on the Minor Planet Center's
'NEOCP' webpage.  Q.-z. Ye reports that three stacked 30-s CCD
exposures obtained with the Lulin Observatory 0.41-m Ritchey-
Chretien reflector on May 12.82 UT show a coma of diameter about 3"
with an apparent but uncertain very faint tail around 7"-10" long
in p.a. about 45 deg.  J. G. Ries writes that her R-band images
obtained with the McDonald Observatory 0.76-m reflector on May 13.4
show the comet to be diffuse with a tail approximately 10"-13" long
toward the north-northeast.  Also, G. Sostero reports that forty
co-added 120-s unfiltered CCD frames taken by L. Donato, M. Gonano,
V. Gonano, E. Guido, and himself with a 0.45-m reflector at
Remanzacco, Italy, during May 13.91-13.98 show a compact coma
nearly 10" in diameter (giving the object's magnitude as 18.7-18.8).

     2007 UT             R.A. (2000) Decl.       Mag.
     May  11.30048   17 40 15.69   +53 06 22.3   19.9

Additional astrometry, the following preliminary parabolic orbital
elements, and an ephemeris appear on MPEC 2007-J55:

     T = 2007 May  11.272 TT          Peri. = 113.384
                                      Node  =  66.274   2000.0
     q = 5.45549 AU                   Incl. =  89.472


COMET P/2007 H1 (McNAUGHT)
     Additional observations of this comet (cf. IAUC 8830),
published on MPEC 2007-J35, yield the following elliptical orbital
elements:

     T = 2007 Aug.  8.740 TT          Peri. = 199.594
     e = 0.42222                      Node  = 144.670   2000.0
     q = 2.31257 AU                   Incl. =  11.802
       a =  4.00251 AU     n = 0.123085     P =   8.0 years

                      (C) Copyright 2007 CBAT
2007 May 13                    (8837)            Daniel W. E. Green