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IAUC 8670: 2006aa, 2006ac,, 2006ad; NO 2006U; 101P

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IAUC number

                                                  Circular No. 8670
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)

SUPERNOVAE 2006aa, 2006ac, AND 2006ad
     The "Nearby Supernova Factory" collaboration reports the
discovery of a type-II supernova (mag approximately 18.9,
calibrated to R) in NEAT images obtained on Feb. 8.3 UT; SN 2006ad
is located at R.A. = 9h07m43s.11, Decl. = +12o03'06".5 (equinox
2000.0).  Details are given on CBET 398, where they also report
that spectroscopy (range 320-1000 nm), obtained on Feb. 10.5-10.6,
shows 2006aa and 2006ac (cf. IAUC 8669) to be type-IIn and type-Ia
supernovae, respectively.

     The "Nearby Supernova Factory" collaboration also reports that
a spectrogram (range 320-1000 nm) of 2006U (cf. IAUC 8667),
obtained on Feb. 8.4 UT with the University of Hawaii 2.2-m
telescope, shows it to be an active galactic nucleus at redshift
0.25.  Details are given on CBET 397.

     Z. Sekanina, Jet Propulsion Laboratory, writes that a
fragmentation solution based on 41 accurate astrometric offsets of
the companion from the principal nucleus in the period 2005 Nov. 3-
2006 Jan. 23 strongly suggests that this companion is not identical
with the secondary nucleus (or nuclei) observed during 1991-1992
(cf. IAUC 5391).  An excellent fit to the 2005-2006 data indicates
that the breakup occurred most probably at a heliocentric distance
of 8-9 AU in late 1996 or early 1997, almost 5 years after the 1992
perihelion, with an uncertainty of +/- 3 months.  The companion's
differential nongravitational deceleration is low but still poorly
defined, 7.5 +/- 5.9 units of 10**-5 solar gravitational
acceleration, whereas the derived separation velocity is 2.0 +/-
0.2 m/s, nearly in the comet's orbital plane.  The companion should
be observable for at least two more months as the comet approaches
its June conjunction with the sun.  It is possible that the
companion could once again be detected from August 2006 on.  The
predicted separation distances and position angles of the companion
relative to the principal nucleus (0h TT, equinox J2000.0):  2006
Feb. 14, 940", 70.0 deg; 24, 909", 70.4 deg; Mar. 6, 879", 71.1
deg; 16, 850", 71.9 deg; 26, 822", 72.8 deg; Apr. 5, 794", 73.9
deg; 15, 767", 75.1 deg; Aug. 23, 488", 93.5 deg; Sept. 2, 476",
94.5 deg; 12, 466", 95.3 deg; 22, 458", 96.1 deg.

                      (C) Copyright 2006 CBAT
2006 February 11               (8670)            Daniel W. E. Green

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