Supernova 2005al

SN 2005al, our fifth discovery, was found on 2005 February 24.16, only sixteen days after the discovery of SN 2005af. Confirmation from IAU came on IAUC 8488. The supernova was located in the galaxy NGC 5304, more precisely at R.A 13^o 50' 00.33" and Dec -30^o 34' 34.2". Its offset from the center of the galaxy was 14”.8 W and 7”.5 N. Apparent (unfiltered) magnitude was measured as 15.1 in the day of discovery.

NGC 5304 is a Southern galaxy most probably belonging to the E+ pec morphological class (although some catalogs list this galaxy as S0). Its apparent integrated magnitude reaches 13.6 and its dimensions are 1.5 x 1.0 arcmin. Given its measured recession speed (3718 +/- 4 km/s) and redshift (0.01240 +/- 0.00001), both from NED data, we can estimate its distance as roughly 53.1 megaparsecs (or some 173 million light years), assuming a Hubble constant of 70 km/s.Mpc.

Absolute magnitude of SN 2005al on its discovery was calculated based on our own photometric measures and on NED data, resulting on Mv = –18.7 (which, coupled to the morphological class of NGC 5304, clearly indicated that the supernova was most likely a Type Ia SN shortly after explosion). A couple of days after (on February 28), a spectrum of 2005al was taken by The Nearby Supernova Factory using the University of Hawaii 2.2-m telescope (ATEL 430) confirming SN 2005al as a Type Ia supernova, most probably close to maximum.