Abstract
Abstract The Cosmology Large Angular Scale Surveyor (CLASS) observes the polarized cosmic microwave background (CMB) over the angular scales of 1° ≲ θ ≤ 90° with the aim of characterizing primordial gravitational waves and cosmic reionization. We report on the on-sky performance of the CLASS Q-band (40 GHz), W-band (90 GHz), and dichroic G-band (150/220 GHz) receivers that have been operational at the CLASS site in the Atacama desert since 2016 June, 2018 May, and 2019 September, respectively. We show that the noise-equivalent power measured by the detectors matches the expected noise model based on on-sky optical loading and lab-measured detector parameters. Using Moon, Venus, and Jupiter observations, we obtain power to antenna temperature calibrations and optical efficiencies for the telescopes. From the CMB survey data, we compute instantaneous array noise-equivalent-temperature sensitivities of 22, 19, 23, and 71 μ K cmb s for the 40, 90, 150, and 220 GHz frequency bands, respectively. These noise temperatures refer to white noise amplitudes, which contribute to sky maps at all angular scales. Future papers will assess additional noise sources impacting larger angular scales.
Highlights
The cosmic microwave background (CMB) polarization is a unique probe to study the origin and evolution of the universe
We report on the on-sky performance of the Cosmology Large Angular Scale Surveyor (CLASS) Q-band (40 GHz), W-band (90 GHz), and dichroic G-band (150/220 GHz) receivers that have been operational at the CLASS site in the Atacama desert since June 2016, May 2018, and September 2019, respectively
We show that the noise-equivalent power measured by the detectors matches the expected noise model based on on-sky optical loading and lab-measured detector parameters
Summary
The cosmic microwave background (CMB) polarization is a unique probe to study the origin and evolution of the universe. CLASS maps the CMB polarization at multiple frequencies and targets both the recombination and reionization peaks from the Atacama desert with the aim of measuring a primordial B-mode signal at a sensitivity level of r ∼ 0.01 and making a near cosmic-variancelimited measurement of τ (Essinger-Hileman et al 2014; Harrington et al 2016; Watts et al 2015; Watts et al 2018). CLASS is designed to be most sensitive at 90 GHz (W band) with two telescopes (Dahal et al 2018; Iuliano et al 2018) optimized for CMB observations near the minimum of polarized Galactic emission.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
