Cosmology Large Angular Scale Surveyor (CLASS): Pointing Stability and Beam Measurements at 90, 150, and 220 GHz

The Cosmology Large Angular Scale Surveyor (CLASS) telescope array surveys 75% of the sky from the Atacama desert in Chile at frequency bands centered near 40, 90, 150, and 220 GHz. CLASS measures the largest-angular-scale CMB polarization with the aim of constraining the tensor-to-scalar ratio, mea...

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Published inarXiv.org
Main Authors Datta, Rahul, Brewer, Michael K, Couto, Jullianna D, Eimer, Joseph R, Li, Yunyang, Xu, Zhilei, Appel, John W, Bustos, Ricardo, Chuss, David T, Cleary, Joseph, Dahal, Sumit, Essinger-Hileman, Thomas, Iuliano, Jeffrey, Marriage, Tobias A, Núñez, Carolina, Petroff, Matthew A, Karwan Rostem, Watts, Duncan J, Wollack, Edward J
Format Paper
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 09.08.2022
Subjects
Cosmology
Frequencies
Ionization
Optical properties
Optical thickness
Sky surveys (astronomy)
Stability
Telescopes
Tensors
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Summary:The Cosmology Large Angular Scale Surveyor (CLASS) telescope array surveys 75% of the sky from the Atacama desert in Chile at frequency bands centered near 40, 90, 150, and 220 GHz. CLASS measures the largest-angular-scale CMB polarization with the aim of constraining the tensor-to-scalar ratio, measuring the optical depth to reionization to near the cosmic variance limit, and more. The CLASS Q-band (40 GHz), W-band (90 GHz), and dichroic high frequency (150/220 GHz) telescopes have been observing since June 2016, May 2018, and September 2019, respectively. On-sky optical characterization of the 40 GHz instrument has been published. Here, we present preliminary on-sky measurements of the beams at 90, 150, and 220 GHz, and pointing stability of the 90 and 150/220 GHz telescopes. The average 90, 150, and 220 GHz beams measured from dedicated observations of Jupiter have full width at half maximum (FWHM) of 0.615+/-0.019 deg, 0.378+/-0.005 deg, and 0.266+/-0.008 deg, respectively. Telescope pointing variations are within a few percent of the beam FWHM.
ISSN:2331-8422