PROTOCALC, A W-band polarized calibrator for CMB Telescopes: application to Simons Observatory and CLASS

• DOI: 10.48550/arxiv.2502.14473
• Publication Date: 2025-02-20
• Authors: Gabriele Coppi; Nadia Dachlythra; F. Nati; Rolando Dünner-Pl...; Alexandre Adler; Josquin Errard; Nicholas Galitzki; Yunyang Li; Matthew A. Petroff; Sara M. Simon; Edward Sang; Ashley Aguilar; Edward J. Wollack; M. Zannoni
• Keywords: Cosmology and Nongalactic Astrophysics (astro-ph.CO); FOS: Physical sciences; [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det]; [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]; Astrophysics - Instrumentation and Methods for Astrophysics; Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics - Cosmology and Nongalactic Astrophysics

Current- and next-generation Cosmic Microwave Background (CMB) experiments will measure polarization anisotropies with unprecedented sensitivities. The need for high precision in these measurements underscores the importance of gaining a comprehensive understanding instrument properties, particular emphasis on study beam properties and, particular, their characteristics, measurement angle. In this context, major challenge lies scarcity millimeter polarized astrophysical sources sufficient brightness calibration knowledge to meet stringent accuracy requirements future CMB missions. This led development drone-borne source designed frequency band centered approximately 90 GHz band, matching commonly used channel ground based measurements. PROTOtype CALibrator Cosmology, PROTOCALC, has undergone thorough in-lab testing, its have been subsequently modeled through simulation software integrated into standard Simons Observatory (SO) analysis pipeline. Moreover, PROTOCALC system tested field, having deployed twice campaigns telescopes Atacama desert. data collected constrain roll angle statistical $0.045^\circ$.