Two-year Cosmology Large Angular Scale Surveyor (CLASS) Observations: 40 GHz Telescope Pointing, Beam Profile, Window Function, and Polarization Performance
Zhilei Xu, Michael K. Brewer, Pedro Fluxá Rojas, Yunyang Li, Keisuke Osumi, Bastián Pradenas, Aamir Ali, John W. Appel, Charles L. Bennett, Ricardo Bustos, Manw… 展开作者
Zhilei Xu, Michael K. Brewer, Pedro Fluxá Rojas, Yunyang Li, Keisuke Osumi, Bastián Pradenas, Aamir Ali, John W. Appel, Charles L. Bennett, Ricardo Bustos, Manwei Chan, David T. Chuss, Joseph Cleary, Jullianna Denes Couto, Sumit Dahal, Rahul Datta, Kevin L. Denis, Rolando Dünner, Joseph R. Eimer, Thomas Essinger-Hileman, Dominik Gothe, Kathleen Harrington, Jeffrey Iuliano, John Karakla, Tobias A. Marriage, Nathan J. Miller, Carolina Núñez, Ivan L. Padilla, Lucas Parker, Matthew A. Petroff, Rodrigo Reeves, Karwan Rostem, Deniz Augusto Nunes Valle, Duncan J. Watts, Janet Weiland, Edward J. Wollack
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 ($1^\circ\lesssimθ\leqslant 90^\circ$) CMB polarization to constrain the tensor-to-scalar ratio at the $r\sim0.01$ level and the optical depth to last scattering to the sample variance limit. This paper presents the optical characterization of the 40 GHz telescope during its first observation era, from 2016 September to 2018 February. High signal-to-noise observations of the Moon establish the pointing and beam calibration. The telescope boresight pointing variation is $<0.023^\circ$ ($<1.6$% of the beam's full width at half maximum (FWHM)). We estimate beam parameters per detector and in aggregate, as in the CMB survey maps. The aggregate beam has an FWHM of $1.579^\circ\pm.001^\circ$ and a solid angle of $838 \pm 6\ μ{\rm sr}$, consistent with physical optics simulations. The corresponding beam window function has a sub-percent error per multipole at $\ell < 200$. An extended $90^\circ$ beam map reveals no significant far sidelobes. The observed Moon polarization shows that the instrument polarization angles are consistent with the optical model and that the temperature-to-polarization leakage fraction is $<10^{-4}$ (95% C.L.). We find that the Moon-based results are consistent with measurements of M42, RCW 38, and Tau A from CLASS's CMB survey data. In particular, Tau A measurements establish degree-level precision for instrument polarization angles.
Design and characterization of the Cosmology Large Angular Scale Surveyor (CLASS) 93 GHz focal plane
宇宙学大角尺度探测器（CLASS）的目标是探测和表征原始B模信号，并对再电离的光学深度进行样本方差有限的测量。CLASS是一种地面多频微波偏振计，每天从阿塔卡马沙漠调查70%的微波天空。所有CLASS望远镜的焦平面探测器阵列都包含光滑壁的喇叭天线，通过对称平面正交模换能器（OMT）天线耦合到过渡边缘传感器（TES）测辐射热计。这些低噪声偏振敏感检测器阵列制造在单晶硅晶片上，以保持TES均匀性并优化整个晶片的光学效率。在本文中，我们讨论了第一类93 GHz探测器阵列的设计和表征。我们测量了探测器的暗参数、带通和噪声谱，并报告探测器是光子噪声限制的。在当前阵列良率为82%的情况下，我们估计总阵列噪声等效功率（NEP）为2.1 aW $\sqrt[]{\mathrm{s}}$。
Two Year Cosmology Large Angular Scale Surveyor (CLASS) Observations: Long Timescale Stability Achieved with a Front-End Variable-delay Polarization Modulator at 40 GHz
Green Bank Telescope: Overview and analysis of metrology systems and pointing performance
绿岸望远镜（Green Bank Telescope，简称GBT）拥有100米x110米的离轴抛物面，是地球上最大的可操控射电望远镜。大型地面射电望远镜面临的一个主要挑战是实现足够的指向精度，以便在高频率下进行观测，在GBT的情况下高达116 GHz。精确指向需要能够盲获取源位置并执行通过观察附近的校准器源确定的特别校正，以便获得精确到目标位置的小误差范围内的起始位置。所需的指向精度取决于半功率波束宽度，对于GBT观测的高频端，这意味着指向必须精确到几弧秒RMS内。GBT的离轴设计是有利的，因为它消除了碟形天线的阻塞并减少了旁瓣干扰，并且没有证据表明由此产生的非对称结构对指向精度产生不利影响。然而，诸如重力弯曲、热变形、方位轨道倾斜和不规则性以及望远镜结构内的小的未对准和偏移误差等因素会导致指向不准确。一个指向模型的GBT，以纠正这些影响。该模型利用标准的几何校正以及来自GBT结构温度传感器的计量数据和来自轨道水平测量的数据。在本文中，我们提供了一个总结的GBT的指向模型和相关的校正，以及相关的计量系统的讨论和分析其目前的夜间指向精度。
The Balloon-borne VLBI Experiment (BVEX) Radio Telescope and Position Tracking System
Queen’s University（女王大学）；Center for Astrophysics — Harvard & Smithsonian（哈佛-史密森尼天体物理中心）；Black Hole Initiative, Harvard University（哈佛大学黑洞倡议）；Dalhousie University（达尔豪斯大学）；Queen’s University, Smith School of Engineering（女王大学史密斯工程学院）；Queen’s University, Department of Mathematics and Statistics（女王大学数学与统计系）；MIT Haystack Observatory（麻省理工学院海斯塔克天文台）；Trottier Space Institute, McGill University（麦吉尔大学特罗蒂尔太空研究所）；McGill University（麦吉尔大学）；McMaster University（麦克马斯特大学）；StarSpec Technologies Inc.（StarSpec科技有限公司）；Johns Hopkins University（约翰斯·霍普金斯大学）；University of British Columbia（不列颠哥伦比亚大学）
The comptonization parameter from simulations of single-frequency, single-dish, dual-beam, cm-wave observations of galaxy clusters and mitigating CMB confusion using the Planck sky survey
QUIJOTE scientific results - XX. Commissioning and First Results from the Thirty and Forty Gigahertz Instrument (TFGI)
Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble Alpes, CNRS/IN2P3（亚原子物理与宇宙学实验室，格勒诺布尔阿尔卑斯大学，法国国家科学研究中心/法国国家粒子物理研究所）；Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Departamento de Astrofísica, Universidad de La Laguna（拉帕尔马大学天体物理学系）；Universidade da Coruña, CITIC（科鲁尼亚大学，信息技术创新中心）；Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), UTIAS, The University of Tokyo（Kavli宇宙物理与数学研究所（ Kavli IPMU, WPI），UTIAS，东京大学）；Instituto de Fisica de Cantabria (IFCA, CSIC-UC)（坎塔布里亚物理研究所（ IFCA, 西班牙国家研究委员会-坎塔布里亚大学））
