Supernova 2004cw

Discovered on 2004 June 13.24, SN 2004cw was the first supernova found by the BRASS team. The SN was located in the galaxy ESO 184-G75, precisely at R.A. 19^o 30' 57.45" and Dec -53^o 32' 28.7". Its offset from the center of ESO 184-G75 was 11”.4 W and 8”.3 N. Apparent (unfiltered) magnitude was measured as 17.2 in the day of discovery.

ESO 184-G75 is a Southern spiral galaxy belonging to the SA(r) c morphological class, having an integrated magnitude of 14.6 and dimensions 1.0 x 0.9 arcmin. Given its measured recession speed (5433 +/- 25 km/s) and redshift (0.01812 +/- 0.00008), both from NED data, we can estimate its distance as roughly 77.6 megaparsecs (or 253 million light years), assuming a Hubble constant of 70 km/s.Mpc. Curiously, this is close to the edge of the distance covered by BRASS search.

Unfortunately, no spectra of 2004cw were taken to obtain the type of this supernova. We can estimate its approximate absolute magnitude, however, from its photometric data, resulting in a raw value of –17.4. Although this value plus the supernova position (right inside the spiral arms of ESO 184-7G5 and close to an HII region) might suggest a Type II SN, no final conclusion may me taken due to the lack of a spectrum.

IAU confirmation to SN 2004cw was given on IAUC 8362.