The Carnegie Supernova Project: The Low‐Redshift Survey

Abstract

ABSTRACT. Supernovae are essential to understanding the chemical evolution of the universe. Type Ia supernovae also provide the most powerful observational tool currently available for studying the expansion history of the universe and the nature of dark energy. Our basic knowledge of supernovae comes from the study of their photometric and spectroscopic properties. However, the presently available data sets of optical and nearinfrared light curves of supernovae are rather small and/or heterogeneous, and employ photometric systems that are poorly characterized. Similarly, there are relatively few supernovae whose spectral evolution has been well sampled, both in wavelength and phase, with precise spectrophotometric observations. The low-redshift portion of the Carnegie Supernova Project (CSP) seeks to remedy this situation by providing photometry and spectrophotometry of a large sample of supernovae taken on telescope/filter/detector systems that are well understood and well characterized. During a 5 year program that began in 2004 September, we expect to obtain high-precision uЈgЈrЈiЈBVYJHK s light curves and optical spectrophotometry for about 250 supernovae of all types. In this paper we provide a detailed description of the CSP survey observing and data reduction methodology. In addition, we present preliminary photometry and spectra obtained for a few representative supernovae during the first observing campaign.

Observational probes of cosmic acceleration

“…Prominent examples include the supernova and weak lensing programs of the CFHT Legacy Survey (CFHTLS; Conley et al 2011;Semboloni et al 2006a;Heymans et al 2012b), the ESSENCE supernova survey (Wood-Vasey et al, 2007), BAO measurements from the Sloan Digital Sky Survey (SDSS; Eisenstein et al 2005;Percival et al 2010;Padmanabhan et al 2012), and the SDSS-II supernova survey . These have been complemented by extensive multi-wavelength studies of local and high-redshift supernovae such as the Carnegie Supernova Project (Hamuy et al, 2006;Freedman et al, 2009), by systematic searches for z > 1 supernovae with Hubble Space Telescope Suzuki et al, 2012), by dark energy constraints from the evolution of X-ray or optically selected clusters (Henry et al, 2009;Vikhlinin et al, 2009;Rozo et al, 2010), by improved measurements of the Hubble constant (Riess et al, , 2011Freedman et al, 2012), and by CMB data from the WMAP satellite (Bennett et al, 2003;Larson et al, 2011) and from ground-based experiments that probe smaller angular scales. 4 Most data remain consistent with a spatially flat universe and a cosmological constant with Ω Λ = 1 − Ω m ≈ 0.75, with an uncertainty in the equation-of-state parameter w that is roughly ±0.1 at the 1 − 2σ level.…”

“…These uncertainties can likely be reduced with detailed, well calibrated, multiwavelength observations of large numbers of low redshift SNe, which can characterize the separate dependence of SN colors on luminosity, light curve shape, and time since explosion, and provide constraints on dust extinction laws that are isolated from cosmological inferences. The final analyses of data from the SDSS-II supernova survey and the low-redshift portion of the Carnegie Supernova Project (Hamuy et al, 2006) should allow advances on this front. Analysis techniques that eliminate the most highly reddened SNe can also reduce extinction systematics if they can be applied in a way that does not introduce selection biases; as an extreme example, one can employ only SNe in early-type galactic hosts, which have low amounts of interstellar dust.…”

Sn Refsdal: Photometry and Time Delay Measurements of the First Einstein Cross Supernova

“…To collapse the multi-band SN Refsdal light curves into a form suitable for use with PyCS, we used a combination of the F125W and F160W observations, which were collected concurrently in almost every epoch, and together have the most complete and well-sampled coverage of the Refsdal light curve. The SNPy software suite was developed by the Carnegie Supernova Project (Hamuy et al 2006) to provide general purpose SN light curve fitting tools, especially for Type Ia SNe. The SNPy spline fitting tools automatically enforce a restriction on the flexibility of the spline curve model by using the "hyperspline" algorithm (Thijsse et al 1998).…”

RISING FROM THE ASHES: MID-INFRARED RE-BRIGHTENING OF THE IMPOSTOR SN 2010da IN NGC 300

“…The observations, the standard data reduction procedure (bias subtraction, flat fielding, and linearity correction) and the photometry calibration was performed by Carnegie Supernova Project collaborators in asimilar way as detailed in Hamuy et al (2006). The field was calibrated in twophotometric nights: 2014 August 1 and 2014 December 20.…”