  We report a radio detection of supernova SN 2004ip in the circumnuclear
region of the luminous infrared galaxy IRAS 18293-3413, using Very Large Array
(VLA) observations at 8.4 GHz on 11 June 2007. SN 2004ip had been previously
discovered at near-infrared wavelengths using adaptive optics observations, but
its nature (core-collapse or thermonuclear) could not be definitely
established. Our radio detection, about three years after the explosion of the
supernova, indicates a prominent interaction of the ejecta of SN 2004ip with
the circumstellar medium, confirming that the supernova was a core-collapse
event (probably Type II), and thus strongly suggesting that its progenitor was
a massive star with a significant mass-loss prior to its explosion. SN 2004ip
has a 8.4 GHz luminosity of 3.5E27 erg/s/Hz, about twice as bright as SN 2000ft
in NGC 7469 at a similar age, and given its projected distance to the nucleus
(~500 pc), is one of the closest of all known radio SNe to a galaxy nucleus,
and one of the brightest radio SNe ever.
