Discovery of two infrared supernovae: A new window on the SN search

We report the discovery of two supernovae (SNe), SN 1999gw and SN 2001db, obtained within the framework of an infrared (2.1 mu m) monitoring campaign of Luminous Infrared Galaxies, aimed at detecting obscured supernovae. SN 2001db, extinguished by AV ~ 5.5 mag, is the first supernova discovered in the infrared that has received the spectroscopic confirmation. This result highlights the power of infrared monitoring in detecting obscured SNe and indicates that optical surveys probably miss a significant fraction of SNe, especially in obscured systems such as starburst galaxies. The preliminary estimate of SN rate in Luminous Infrared Galaxies is about an order of magnitude higher than that expected from optical surveys. Based on observations obtained at the ESO-NTT in La Silla, at the ESO-VLT in Paranal and at the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Centro Galileo Galilei of the CNAA (Consorzio Nazionale per l'Astronomia e l'Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.