Supernova 2004cz

SN 2004cz, our second discovery, was found on 2004 June 26.33, only thirteen days after the discovery of SN 2004cw. Confirmation from IAU came on IAUC 8368. The supernova was located in the galaxy ESO 407-G09, more precisely at R.A. 23^o 12' 43.22" and Dec -37^o 12' 58.7". Its offset from the center of the galaxy was 24”.6 W and 30”.4 S. Apparent (unfiltered) magnitude was measured as 15.0 in the day of discovery; it was the brightest SN in the sky at that time.

ESO 407-G09 is a Southern galaxy belonging to the SB(s) d morphological class, having an integrated magnitude of 14.7 and dimensions 1.9 x 0.7 arcmin. Given its measured recession speed (1571 +/- 10 km/s) and redshift (0.00524 +/- 0.00003) , both from NED data, we can estimate its distance as roughly 22.4 megaparsecs (or some 73 million light years), assuming a Hubble constant of 70 km/s.Mpc.

Spectra of 2004cz, taken on July 18 by Filippenko, Foley and Pugh from University of California, Berkeley (IAUC 8374), showed this supernova to be of class IIP. The spectra showed well-developed P-Cygni profiles of H, Ca II, Fe II, and other species. Those results are quite consistent with our own photometric data, which show for SN 2004cz on discovery an absolute magnitude of –16.8 (which is typical for a SN of that class a few weeks after explosion).