/ 05 06 43 6 v 2 2 A ug 2 00 5 Luminosity and mass limits for the progenitor of the type Ic supernova 2004 gt in NGC 4038

We report our attempts to locate the progenitor of the type Ic SN 2004gt in NGC 4038. We use high resolution HST ACS images of SN 2004gt and have compared them with deep pre-explosion HST WFPC2 F336W, F439W, F555W and F814W images. We identify the SN location on the pre-explosion frames with an accuracy of 5mas. We show that the progenitor is below the detection thresholds of all the pre-explosion images. These detection limits are used to place luminosity and mass limits on the progenitor. The progenitor of SN 2004gt seems to be restricted to a low-luminosity high-temperature star, either a single WC star with initial mass > 40M⊙ or a low mass star in a binary. The preexplosion data cannot distinguish between the two scenarios. Subject headings: stars:evolution—supernovae:general—supernovae:individual(2004gt)— galaxies:individual(NGC 4038)