Title:	Holographic Beam Measurements of the Canadian Hydrogen Intensity Mapping Experiment (CHIME)
Authors:	Amiri, Mandana Chakraborty, Arnab Foreman, Simon Halpern, Mark Hill5, Alex S. Hinshaw, Gary Landecker, T. L. MacEachern, Joshua Masui, Kiyoshi W. Mena-Parra, Juan Milutinovic, Nikola Newburgh, Laura Ordog, Anna Pen, Ue-Li Pinsonneault-Marotte, Tristan Reda, Alex Siegel, Seth R. Singh, Saurabh Wang, Haochen Wulf, Dallas The CHIME Collaboration
Issue Date:	20-Nov-2024
Publisher:	IOP Publishing Ltd
Citation:	The Astrophysical Journal, 2024, Vol. 976, p163
Abstract:	We present the first results of the holographic beam-mapping program for the Canadian Hydrogen Intensity Mapping Experiment (CHIME). We describe the implementation of a holographic technique as adapted for CHIME, and introduce the processing pipeline which prepares the raw holographic timestreams for analysis of beam features. We use data from six bright sources across the full 400–800 MHz observing band of CHIME to provide measurements of the copolar and cross-polar beam response in both amplitude and phase for all 1024 dual-polarized feeds in the array. In addition, we present comparisons with independent probes of the CHIME beam, which indicate the presence of polarized beam leakage. Holographic measurements of the beam have already been applied in science with CHIME, e.g., in estimating the detection significance of far-sidelobe fast radio bursts, and in validating the beam models used for CHIME's first detections of 21 cm emission (in cross-correlation with measurements of large-scale structure from galaxy surveys and the Lyα forest). Measurements presented in this paper, and future holographic results, will provide a unique data set to characterize the CHIME beam and improve the experiment's prospects for a detection of the baryon acoustic oscillation signal.
Description:	Open Access
URI:	http://hdl.handle.net/2289/8358
Alternative Location:	https://ui.adsabs.harvard.edu/abs/2024ApJ...976..163A/abstract https://arxiv.org/abs/2408.00172 https://doi.org/10.3847/1538-4357/ad8133
Copyright:	2024 IOP Publishing Ltd.
Appears in Collections:	Research Papers (A&A)

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