[IAUC] CBET 858: 20070224 : SUPERNOVA 2004ip IN IRAS 18293-3413 = PSN K0409-001

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                                                  Electronic Telegram No. 858
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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SUPERNOVA 2004ip IN IRAS 18293-3413 = PSN K0409-001
      S. Mattila, Queen's University Belfast, and his colleagues (P.
Vaisanen, P. Meikle, T. Dahlen, A. Efstathiou, D. Farrah, C. Fransson, P.
Lira, P. Lundqvist, G. Ostlin, S. Ryder, and J. Sollerman) report the
discovery of an apparent supernova in K_s-band images obtained using the
NAOS CONICA adaptive optics system on the European Southern Observatory's
Very Large Telescope (VLT).  The new object was first observed on 2004
Sept. 13.1 UT and Sept. 15.0 at K_s = 18.7 +/- 0.1, and again on Sept. 27.1
UT at K_s = 18.9 +/- 0.15.  SN 2004ip, which was designated PSN K0409-001
by the Central Bureau in September 2004 (and posted at
http://cfa-www.harvard.edu/iau/CBAT_PSN.html), is located within the
nuclear regions of the luminous infrared galaxy (LIRG) IRAS 18293-3413 at
R.A. = 18h32m41s.26, Decl. = -34o11'26".7 (equinox 2000.0), which is 1".14
east and 0".78 north of (or 500 pc from) the galaxy's Ks-band nucleus.  The
apparent supernova was detected via image-subtraction techniques using a
reference K_s-band image obtained under similar conditions on 2004 May 4.3
with the VLT/NACO as part of a search campaign for highly obscured
supernovae.  Its luminosity and light curve are consistent with a
core-collapse event with a likely extinction of between about 5 and 40
magnitudes in V (Mattila et al. 2007, astro-ph/0702591).
      Mattila adds that explanations other than a supernova for this object
are extremely unlikely.  SN 2004ip is located within a circumnuclear
starburst of its host galaxy which has an infrared SED consistent with no
contribution from an active-galactic nucleus (AGN).  Also, Mannucci et al.
(2003, A.Ap. 401, 519) monitored IRAS 18293-3413 in K_s-band for 2.5
years, finding no variability within the nuclear regions.  A line-of-sight
variable foreground star superimposed on the central-kiloparsec regions of
this galaxy (a search area of only about 8 square arcsec) is considered
highly unlikely, such stars have not been observed elsewhere in the
observation program by Mattila et al., involving 15 galaxies.  Also, large
numbers of supernovae are expected in the nuclear regions of starburst
galaxies and LIRGs as a result of the large star-formation rates therein
(e.g., Mattila and Meikle 2001, MNRAS 324, 325; Mattila et al. 2004, New
Astronomy Rev. 48, 595).  Mattila et al. found SNe 2005U and 2005V during
a K_s-band search over ten nights for supernovae near galactic nuclei with
the 4.2-m William Herschel Telescope in a sample of nearby starburst
galaxies, while Mannucci et al. (2003, op.cit.) found SNe 1999gw and
2001db in their K_s-band search for obscured supernovae in a sample of
more distant LIRGs.
      SN 2004ip appears to be the first such object discovered through the
use of adaptive optics.  Follow-up radio observations of this apparent
supernova are encouraged.


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                         (C) Copyright 2007 CBAT
2007 February 24                 (CBET 858)               Daniel W. E. Green