Early Photometry Studies for Euclid

Abstract

The Euclid mission aims to investigate the distance-redshift relationship and the evolution of cosmic structures by measuring shapes and redshifts of galaxies and clusters of galaxies. Data from the satellite instruments will be merged with ground based imaging data from large surveys such as the Dark Energy Survey and Pan-STARRS. Euclid_s14s weak galaxy lensing experiment requires very accurate photometric redshifts and thus precise galaxy colours. In this contribution we compare the ‘traditional approach’ of fitting object models to co-added images with a new technique that simultaneously fits a model to the ensemble of individual images. Preliminary results indicate that the photometry using individual image fitting is more precise.