Feeding the Pipeline: The SNfactory Search for Nearby Supernovae

Richard Scalzo, Lawrence Berkeley Lab

Measurements in recent years of the rate of acceleration of the universe's expansion, and of the density of "dark energy" believed to be driving it, hinge on observations of type Ia supernovae (SNe Ia). The Nearby Supernova Factory (SNfactory) will produce flux-calibrated spectrophotometry of 300 SNe Ia in the local universe (0.03 < z < 0.08). This new data set will greatly increase the number of SNe Ia available for cosmological measurements in this redshift range, reducing statistical uncertainties on cosmological parameters. Analysis of spectral time series from the SNfactory will provide new insights into the progenitors of SNe Ia, the mechanisms by which they explode, and the measures necessary to improve the calibration of the brightness of SNe Ia for use in the next generation of dark energy experiments.

In this talk I will discuss the structure and performance of the software pipeline which provides the SNfactory with candidates for observing targets. Each night the pipeline processes about 30,000 images (60 GB of data), covering some 400 square degrees of the sky, and performs an automated search for supernova candidates. The pipeline runs on the Parallel Distributed Systems Facility (PDSF) at NERSC, using 400 CPU-hours per night. At present the pipeline produces some 15 SNe Ia per month.