The Carnegie Supernova Project: The Low‐Redshift Survey

Supernovae are essential to understanding the chemical evolution of theUniverse. Type Ia supernovae also provide the most powerful observational toolcurrently available for studying the expansion history of the Universe and thenature of dark energy. Our basic knowledge of supernovae comes from the studyof their photometric and spectroscopic properties. However, the presentlyavailable data sets of optical and near-infrared light curves of supernovae arerather small and/or heterogeneous, and employ photometric systems that arepoorly characterized. Similarly, there are relatively few supernovae whosespectral evolution has been well sampled, both in wavelength and phase, withprecise spectrophotometric observations. The low-redshift portion of theCarnegie Supernova Project (CSP) seeks to remedy this situation by providingphotometry and spectrophotometry of a large sample of supernovae taken ontelescope/filter/detector systems that are well understood and wellcharacterized. During a five-year program which began in September 2004, weexpect to obtain high-precision u'g'r'i'BVYJHKs light curves and opticalspectrophotometry for about 250 supernovae of all types. In this paper weprovide a detailed description of the CSP survey observing and data reductionmethodology. In addition, we present preliminary photometry and spectraobtained for a few representative supernovae during the first observingcampaign.Comment: 45 pages, 13 figures, 3 tables, accepted by PAS