Status and future development of the COSMOCal Project for absolute CMB polarization calibration

arXiv:2607.12698 · astro-ph.IM, astro-ph.CO · Submitted 2026-07-14 · Read on arXiv

Silvia Micheli, Alessia Ritacco, Alessandro Carones, Jonathan Aumont, Stefano Berta, Ludovico Bizzarri, François Boulanger, Andrea Catalano, Francesco Cuttaia, Anne Denis, François-Xavier Désert, Anne Laure Fontana, David González-Ovejero, Benedetta Kalemi, Nicoletta Krachmalnicoff, Samuel Leclercq, Thibaut Louis, Juan-Francisco Macías-Pérez, Bruno Maffei, Tania Mcnamara, Marina Migliaccio, Ludovic Montier, Pascal Morfin, Michel Moulin, Louise Mousset, Matteo Murgia, Ioannis Myserlis, Federico Nati, Pierluigi Ortu, Michel Pérault, Giampaolo Pisano, Tonino Pisanu, Nicolas Ponthieu, Sofia Savorgnano, Luca Terenzi, Jeanne Treuttel, Léo Vacher, Christophe Vescovi, Mario Zannoni

astro-ph.IM, astro-ph.CO

Submitted: 2026-07-14

Comments: Submitted to Proceedings of SPIE, Astronomical Telescopes + Instrumentation 2026. 12 pages, 3 figures

License: http://creativecommons.org/licenses/by/4.0/

The gist: Cosmic Microwave Background (CMB) polarization measurements are pushing instrumental sensitivities to levels where calibration systematics become a dominant limitation.

Terminology

Calibration — 56× in this paper · explained in 7 episodes
Accuracy — 9× in this paper · explained in 1 episode
Cosmic Microwave Background — 9× in this paper
Aperture — 6× in this paper · explained in 1 episode
Anisotropy — 5× in this paper · explained in 3 episodes
Simons Observatory — 4× in this paper
Benchmark — 3× in this paper · explained in 2 episodes
Degeneracy — 3× in this paper · explained in 3 episodes
Internal Linear Combination — 3× in this paper
Spectral Distortions — 3× in this paper · explained in 2 episodes
Clustering — 2× in this paper · explained in 2 episodes
Spectral Energy Distribution — 2× in this paper
Adam — 1× in this paper · explained in 2 episodes
Fidelity — 1× in this paper · explained in 2 episodes
Frequency Dependence — 1× in this paper · explained in 2 episodes
Hybrid Approach — 1× in this paper · explained in 4 episodes
Nine-year Wilkinson Microwave Anisotropy Probe — 1× in this paper
Robustness — 1× in this paper · explained in 5 episodes
Signal-to-noise ratio (SNR) — 1× in this paper · explained in 2 episodes
Systematic Bias — 1× in this paper · explained in 3 episodes
Telescope and the Sardinia Radio Telescope — 1× in this paper

Abstract

Cosmic Microwave Background (CMB) polarization measurements are pushing instrumental sensitivities to levels where calibration systematics become a dominant limitation. The large dynamic range between cosmological and Galactic emission prevents future experiments from relying only on diffuse sky measurements or standard celestial calibrators. To address this challenge, the COSmological Microwave Observations Calibrator (COSMOCal) project proposes an artificial calibration source deployed as a guest payload on a geostationary satellite, scheduled for launch by the Eutelsat group by 2030. This source will provide stable, well-characterized polarized microwave signals accessible to multiple ground-based observatories. In this work, we present the status of the project, the updated development timeline, and the refined scientific and technical requirements, defined with the observatories that plan to use this calibration source. Furthermore, we investigate the interplay between instrumental systematics and component separation in the presence of complex models of interstellar dust emission. We discuss in this paper how this can impact the recovery of the primordial signal, and whether residual calibration errors can degrade the performance of foreground cleaning algorithms.

Status and future development of the COSMOCal Project for absolute CMB polarization calibration

Terminology

Abstract

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