Characterization of the John A. Galt Telescope for radio holography with CHIME
Characterization of the John A. Galt Telescope for radio holography with CHIME
复制标题
DOI：
10.1117/12.2629429
复制
发表时间：
2022-07
期刊：
影响因子：
--
通讯作者：
A. Reda;T. Pinsonneault-Marotte;M. Deng;M. Amiri;K. Bandura;A. Chakraborty;S. Foreman;A. Hill;Joseph W. Kania;Joshua MacEachern;K. Masui;L. Newburgh;S. Paul;S. Siegel;R. Smegal;Haochen Wang;D. Wulf
中科院分区：
文献类型：
--
作者：
A. Reda;T. Pinsonneault-Marotte;M. Deng;M. Amiri;K. Bandura;A. Chakraborty;S. Foreman;A. Hill;Joseph W. Kania;Joshua MacEachern;K. Masui;L. Newburgh;S. Paul;S. Siegel;R. Smegal;Haochen Wang;D. Wulf
加拿大氢强度测绘实验(CHME)将测量天体物理中性氢的21厘米发射，以探测红移z=0.8-2.5的大尺度结构。然而，在更明亮的前景下检测21厘米的信号仍然是一个关键挑战。由于21厘米和前景发射之间的高动态范围，需要对仪器系统进行精确的校准，特别是望远镜光束，才能成功滤除前景。一种用于实现钟声光束的高保真测量的技术是无线电全息术，其中来自CHINE的每个模拟输入的信号与来自同一位置的参考天线的信号相关，该参考天线是26米的约翰·A·高尔特望远镜，当26米高尔特望远镜跟踪经过CHINE的亮点源时。在这项工作中，我们分析了高尔特望远镜的几个特性。我们使用几个亮源的漂移扫描测量，以及从408 MHz Haslam图得出的背景估计，来估计Galt系统的温度。为了确定Galt望远镜的光束形状，我们对明亮的射电光源仙后座A进行了光栅扫描并进行了分析。最后，我们使用早期的全息测量来测量Galt望远镜相对于CHINE的几何形状，用于CHINE-GALT干涉数据集的全息分析。
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) will measure the 21 cm emission of astrophysical neutral hydrogen to probe large scale structure at redshifts z = 0.8–2.5. However, detecting the 21 cm signal beneath substantially brighter foregrounds remains a key challenge. Due to the high dynamic range between 21 cm and foreground emission, an exquisite calibration of instrument systematics, notably the telescope beam, is required to successfully filter out the foregrounds. One technique being used to achieve a high fidelity measurement of the CHIME beam is radio holography, wherein signals from each of CHIME’s analog inputs are correlated with the signal from a co-located reference antenna, the 26 m John A. Galt telescope, as the 26 m Galt telescope tracks a bright point source transiting over CHIME. In this work we present an analysis of several of the Galt telescope’s properties. We employ drift-scan measurements of several bright sources, along with background estimates derived from the 408 MHz Haslam map, to estimate the Galt system temperature. To determine the Galt telescope’s beam shape, we perform and analyze a raster scan of the bright radio source Cassiopeia A. Finally, we use early holographic measurements to measure the Galt telescope’s geometry with respect to CHIME for the holographic analysis of the CHIME-Galt interferometric data set.