Mirage: A new iterative map-making code for CMB experiments

¹ CEA-CE Saclay, DAPNIA, Service de Physique des Particules, Bât. 141, 91191 Gif-sur-Yvette Cedex, France e-mail: yvon@hep.saclay.cea.fr
² Fédération de Recherche APC, Université Paris 7, Paris, France
³ LPSC Grenoble, CNRS/IN2P3 and Université J. Fourier, 53 avenue des Martyrs, 38026 Grenoble Cedex, France

Received: 19 December 2003
Accepted: 10 January 2005

Abstract

A major goal of CMB experiments is to obtain highly sensitive CMB maps in order to extract Spherical Harmonic Power Spectrum (SHPS) and cosmological parameters with unprecedented accuracy. We present a new map-making code (Mirage) based on a two-phase iterative algorithm, involving low frequency drift treatment, Butterworth high-pass filtering, and conjugate gradient method. This work was strongly motivated by Archeops CMB experiment data analysis, which we believe is a good test bench for future Planck Surveyor data analysis. Mirage was designed to be used for Planck data processing with a minimum amount of effort. A strong feature of Mirage is that it handles experimental problems in data, such as holes in the data stream, bright sources, and galaxy side effects, without jeopardising speed. The other advantage is its processing speed that allows Monte Carlo simulations of Archeops data processing to be run overnight on a single processor workstation. Algorithms are explained and systematic effects on SHPS investigated on various simulated data, including typical Archeops observational systematics. The code is now available at http://www-dapnia.cea.fr/Telechargement/tel_mirage.php