Distance to the Active Galaxy NGC 6951 via the Type Ia Supernova 2000E

Abstract

CCD-photometry and low-resolution spectroscopy of the bright supernova SN 2000E in NGC 6951 are presented. Both the light curve extending up to 150 days past maximum and the spectra obtained at 1 month past maximum confirm that SN 2000E is of Type Ia. The reddening of SN 2000E is determined as E(B-V)=0.36+/-0.15, its error is mainly due to uncertainties in the predicted SN (B-V) colour at late epochs. The V(RI)_C light curves are analyzed with the Multi-Colour Light Curve Shape (MLCS) method. The shape of the late light curve suggests that SN 2000E was overluminous by about 0.5 mag at maximum comparing with a fiducial SN Ia. This results in an updated distance of 33+/-8 Mpc of NGC 6951 (corrected for interstellar absorption). The SN-based distance modulus is larger by about +0.7 mag than the previous Tully-Fisher estimates. However, possible systematic errors due to ambiguities in the reddening determination and estimates of the maximum luminosity of SN 2000E may plague the present distance measurement.