Low-Redshift Type Ia Supernovae by the Carnegie Supernova Project, Gastón Folatelli (Universidad de Chile)

I will present the analysis of the first set of 35 low-redshift (z<0.08) Type Ia supernovae studied by the Carnegie Supernova Project. The data consist of densely-sampled, high-precision light curves obtained with a uniform, well-characterized photometric system comprising the u'g'r'i'BVYJHKs bands. I will show how we used these data to derive light-curve parameters and to build template light curves that
are applicable for fitting other Type-Ia supernova data. Also, I will present our calibration of intrinsic colors at maximum light and color excesses which allowed us to study the properties of the reddening law in the host galaxies, with the advantage of combining optical and NIR bands. The main goal of the analysis was to produce a calibration of absolute peak magnitudes in all bands versus decline rates and color (or reddening). Such calibrations yielded dispersions of ~0.12 mag (~6% dispersion in distance!), and low values of the reddening-law parameter Rv ~1 - 2. I will further discuss the validity of Type-Ia supernovae as true *standard candles* (i.e. requiring no correction for decline rate) in the NIR.