EZ: A Tool for Automatic Redshift Measurement

TL;DR

EZ is an open-source tool designed for automatic, reliable redshift measurement from optical spectra, suitable for large surveys, with both automated and interactive capabilities, validated on real and simulated data.

Contribution

The paper introduces EZ, a new open-source software that automates redshift measurement with high reliability for large spectroscopic surveys.

Findings

Successfully used in VVDS and zCosmos projects

Achieves high accuracy on simulated data

Provides both automatic and interactive analysis modes

Abstract

We present EZ (Easy redshift), a tool we have developed within the VVDS project to help in redshift measurement from otpical spectra. EZ has been designed with large spectroscopic surveys in mind, and in its development particular care has been given to the reliability of the results obtained in an automatic and unsupervised mode. Nevertheless, the possibility of running it interactively has been preserved, and a graphical user interface for results inspection has been designed. EZ has been successfully used within the VVDS project, as well as the zCosmos one. In this paper we describe its architecture and the algorithms used, and evaluate its performances both on simulated and real data. EZ is an open source program, freely downloadable from http://cosmos.iasf-milano.inaf.it/pandora.