Supernova 2004ew

SN 2004ew, our third discovery, was found on 2004 October 08.18. Confirmation from IAU came on IAUC 8418. The supernova was located in the galaxy ESO 153-G17, more precisely at R.A. 02^o 05' 06.17" and Dec -55^o 06' 31.6". Its offset from the center of the galaxy was 5”.6 E and 12”.1 N. Apparent (unfiltered) magnitude was estimated as 18.8 in the day of discovery; however, we found this to be only a very rough estimate.

ESO 153-G17 is a Southern galaxy belonging to the SAB(r) bc morphological class, having an integrated magnitude of 12.1 and dimensions 2.6 x 1.9 arcmin. Given its measured recession speed (6529 +/- 10 km/s) and redshift (0.02178 +/- 0.00003), both from NED data, we can estimate its distance as roughly 93.3 megaparsecs (or some 304 million light years), assuming a Hubble constant of 70 km/s.Mpc.

Spectra of 2004ew have shown this supernova to be of Type Ib. A multi-wavelength light curve of this supernova is available from Carnegie Supernovae Program at the URL http://csp1.lco.cl/~cspuser1/images/OPTICAL_LIGHT_CURVES/SN04ew.html. From CSP’s V light curve plus our own data it appears that SN 2004ew had its absolute magnitude on discovery in the neighborhood of –17.