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IAUC 8494: COMET C/2005 E2 (McNAUGHT); C/2005 E3

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IAUC number

                                                  Circular No. 8494
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

     R. H. McNaught reports his discovery of a comet with a 12"
tail in p.a. 250 deg on CCD images taken on Mar. 12.8 and 13.8 UT
with the 0.5-m Uppsala Schmidt telescope at Siding Spring
(discovery observation given below).  Following posting on the 'NEO
Confirmation Page', CCD observations obtained with the 1.0-m f/7.7
reflector at Mt. John University Observatory on Mar. 13.7 by A. C.
Gilmore (measured by P. M. Kilmartin) show a uniform coma about 7"
in diameter with a stubby tail 13" long to the southwest.

     2005 UT             R.A. (2000) Decl.       Mag.
     Mar. 12.75009   19 47 24.43   -35 48 32.6   16.5

The available astrometry, the following very preliminary parabolic
orbital elements, and an ephemeris appear on MPEC 2005-E84.

     T = 2006 Apr. 13.126 TT          Peri. = 358.748
                                      Node  = 357.427   2000.0
     q = 3.01128 AU                   Incl. =  16.116

COMETS C/2005 E3 (SOHO) AND C/2005 E4 (SOHO)
     Additional comets found on SOHO website images (cf. IAUC 8490;
MO = M. Oates).

 Comet       2005 UT       R.A.(2000)Decl.  Inst.  F    MPEC
 C/2005 E3   Mar.  6.671   23 16.9  - 6 09   C2    MO   2005-E87
 C/2005 E4        10.388   23 33.0  - 2 48   C3    RK   2005-E87

C/2005 E3 is a Kreutz sungrazer, while C/2005 E4 belongs to the
Marsden group.  On MPEC 2005-E87, B. G. Marsden suggests that
C/2005 E4 is identical with C/1999 N5 and has P = 5.66 yr.  He
shows that, when run back a further revolution, the linked orbit
agrees very closely with the linked orbit corresponding to his
earlier suggestion that C/2004 V9 was a return of C/1999 J6 (IAUC
8456, MPEC 2004-X73, P = 5.49 yr), with then T = 1993 Nov. 20-22, q
= 0.0515 AU, and agreement to better than 0.3 deg in Peri., Node,
and i.  This indicates that these Marsden-group comets probably
separated from each other around that time.  Marsden adds that, if
C/1999 U2 also then separated from them, it would now have P = 5.95
yr and T = 2005 Oct. 8 (to within a few days).

                      (C) Copyright 2005 CBAT
2005 March 16                  (8494)            Daniel W. E. Green

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