High Precision Photometry in Supernova Cosmology
The Supernova Legacy Survey (SNLS) is a 5 year survey of distant supernovae. Its aim is to construct a Hubble diagram in a redshift range from 0.2 to 1. Photometry is the fundamental analysis tool of supernova cosmology, allowing us to compute the flux of the objects using the images obtained during the survey. We will begin with a broad overview of supernova cosmology with emphasis on the methods used by SNLS. Here we will introduce the concept of PSF photometry, then move onto its validation using simulations. We then address issues relating to calibration of the obtained fluxes. We conclude with a brief discussion on flux calibration uncertainty, and its relevance in the next generation of supernova cosmology experiments.