The Astrophysical Journal Supplement Series (Jan 2024)
Cosmology Large Angular Scale Surveyor (CLASS): 90 GHz Telescope Pointing, Beam Profile, Window Function, and Polarization Performance
- Rahul Datta,
- Michael K. Brewer,
- Jullianna Denes Couto,
- Joseph Eimer,
- Yunyang Li,
- Zhilei Xu,
- Aamir Ali,
- John W. Appel,
- Charles L. Bennett,
- Ricardo Bustos,
- David T. Chuss,
- Joseph Cleary,
- Sumit Dahal,
- Francisco Raul Javier Espinoza Inostroza,
- Thomas Essinger-Hileman,
- Pedro Fluxá,
- Kathleen Harrington,
- Kyle Helson,
- Jeffrey Iuliano,
- John Karakla,
- Tobias A. Marriage,
- Sasha Novack,
- Carolina Núñez,
- Ivan L. Padilla,
- Lucas Parker,
- Matthew A. Petroff,
- Rodrigo Reeves,
- Karwan Rostem,
- Rui Shi,
- Deniz A. N. Valle,
- Duncan J. Watts,
- Janet L. Weiland,
- Edward J. Wollack,
- Lingzhen Zeng
Affiliations
- Rahul Datta
- ORCiD
- Department of Astronomy and Astrophysics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USA ; [email protected]; The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Michael K. Brewer
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Jullianna Denes Couto
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Joseph Eimer
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Yunyang Li
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Zhilei Xu
- ORCiD
- MIT Kavli Institute, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Department of Physics and Astronomy, University of Pennsylvania , 209 South 33rd Street, Philadelphia, PA 19104, USA
- Aamir Ali
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- John W. Appel
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Charles L. Bennett
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Ricardo Bustos
- ORCiD
- Departamento de Ingeniería Eléctrica, Universidad Católica de la Santísima Concepción , Alonso de Ribera 2850, Concepción, Chile
- David T. Chuss
- ORCiD
- Department of Physics, Villanova University , 800 Lancaster Avenue, Villanova, PA 19085, USA
- Joseph Cleary
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Sumit Dahal
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA; NASA Goddard Space Flight Center , 8800 Greenbelt Road, Greenbelt, MD 20771, USA
- Francisco Raul Javier Espinoza Inostroza
- ORCiD
- Departamento de Ingeniería Eléctrica, Universidad Católica de la Santísima Concepción , Alonso de Ribera 2850, Concepción, Chile
- Thomas Essinger-Hileman
- ORCiD
- NASA Goddard Space Flight Center , 8800 Greenbelt Road, Greenbelt, MD 20771, USA
- Pedro Fluxá
- Instituto de Astrofísica, Pontificia Universidad Católica de Chile , Vicuña Mackenna 4860, Chile
- Kathleen Harrington
- ORCiD
- Department of Astronomy and Astrophysics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USA ; [email protected]; High Energy Physics Division, Argonne National Laboratory , 9700 S. Cass Avenue, Argonne, IL 60439, USA
- Kyle Helson
- ORCiD
- NASA Goddard Space Flight Center , 8800 Greenbelt Road, Greenbelt, MD 20771, USA; Center for Space Sciences and Technology, University of Maryland Baltimore County , Baltimore, MD 21250, USA; Center for Research and Exploration in Space Science and Technology , NASA/GSFC, Greenbelt, MD 20771, USA
- Jeffrey Iuliano
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA; Department of Physics and Astronomy, University of Pennsylvania , 209 South 33rd Street, Philadelphia, PA 19104, USA
- John Karakla
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Tobias A. Marriage
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Sasha Novack
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Carolina Núñez
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Ivan L. Padilla
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Lucas Parker
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA; Space and Remote Sensing, MS D436, Los Alamos National Laboratory , Los Alamos, NM 87544, USA
- Matthew A. Petroff
- ORCiD
- Center for Astrophysics , Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
- Rodrigo Reeves
- ORCiD
- CePIA, Departamento de Astronomía, Universidad de Concepción , Concepción, Chile
- Karwan Rostem
- ORCiD
- NASA Goddard Space Flight Center , 8800 Greenbelt Road, Greenbelt, MD 20771, USA
- Rui Shi
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Deniz A. N. Valle
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Duncan J. Watts
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA; Institute of Theoretical Astrophysics, University of Oslo , P.O. Box 1029 Blindern, N-0315 Oslo, Norway
- Janet L. Weiland
- ORCiD
- The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3701 San Martin Drive, Baltimore, MD 21218, USA
- Edward J. Wollack
- ORCiD
- NASA Goddard Space Flight Center , 8800 Greenbelt Road, Greenbelt, MD 20771, USA
- Lingzhen Zeng
- ORCiD
- Center for Astrophysics , Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
- DOI
- https://doi.org/10.3847/1538-4365/ad50a0
- Journal volume & issue
-
Vol. 273,
no. 2
p. 26
Abstract
The Cosmology Large Angular Scale Surveyor (CLASS) is a telescope array that observes the cosmic microwave background (CMB) over ∼75% of the sky from the Atacama Desert, Chile, at frequency bands centered near 40, 90, 150, and 220 GHz. CLASS measures the large angular scale CMB polarization to constrain the tensor-to-scalar ratio and the optical depth to last scattering. This paper presents the optical characterization of the 90 GHz telescope. Observations of the Moon establish the pointing while dedicated observations of Jupiter are used for beam calibration. The standard deviations of the pointing error in azimuth, elevation, and boresight angle are 1.′3, 2.′1, and 2.′0, respectively, over the first 3 yr of observations. This corresponds to a pointing uncertainty ∼7% of the beam’s full width at half-maximum (FWHM). The effective azimuthally symmetrized instrument 1D beam estimated at 90 GHz has an FWHM of 0.°620 ± 0.°003 and a solid angle of 138.7 ± 0.6(stats.) ± 1.1(sys.) μ sr integrated to a radius of 4°. The corresponding beam window function drops to ${b}_{{\ell }}^{2}=0.93,0.71,0.14$ at ℓ = 30, 100, 300, respectively. Far-sidelobes are studied using detector-centered intensity maps of the Moon and measured to be at a level of 10 ^−3 or below relative to the peak. The polarization angle of Tau A estimated from preliminary survey maps is 149°.6 ± 0°.2(stats.) in equatorial coordinates. The instrumental temperature-to-polarization ( T → P ) leakage fraction, inferred from per-detector demodulated Jupiter scan data, has a monopole component at the level of 1.7 × 10 ^−3 , a dipole component with an amplitude of 4.3 × 10 ^−3 , with no evidence of quadrupolar leakage.
Keywords
- Astronomical instrumentation
- Telescopes
- Polarimeters
- Cosmic microwave background radiation
- Observational cosmology
