The Nearby Supernova Factory dataset-improving SNe Ia as dark energy probes

During the 2004–2008 period the Nearby Supernova Factory discovered ∼1000 supernovae, and obtained detailed spectrophotometric time series of ∼190 SNe Ia with the SuperNova Integral Field Spectrograph. These supernovae are located in the nearby Hubble flow (0.03peculiar velocities and bulk flows. Each supernova was spectrophotometrically observed over a period of ∼50 days, with a median number of 15 observations per target. The first spectrum is typically obtained at ‐4 days, and in some instances as early as ‐14 days before maximum light. Each spectrum (3200A–10000A) is photometrically calibrated, with simultaneous observations of field stars used to correct for atmospheric extinction variability.The first results, impacting the use of SNe Ia as dark energy probes, are presented. We discuss how the SNfactory dataset can be used to find correlations between spectroscopic and photometric properties of SNe Ia, and demonstrate a ...