Electronic Telegram No. 858 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html 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. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2007 CBAT 2007 February 24 (CBET 858) Daniel W. E. Green