Holographic Beam Measurements of the Canadian Hydrogen Intensity Mapping Experiment (CHIME)

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 the 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 co-polar and cross-polar beam response of CHIME in both amplitude and phase for the 1024 dual-polarized feeds instrumented on CHIME. In addition, we present comparisons with independent probes of the CHIME beam which indicate the presence of polarized beam leakage in CHIME. Holographic measurements of the CHIME beam have already been applied in science with CHIME, e.g. in estimating detection significance of far sidelobe FRBs, and in validating the beam models used for CHIME's first detections of \tcm emission (in cross-correlation with measurements of large-scale structure from galaxy surveys and the Lyman-$\alpha$ 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 BAO.

submitted to ApJ

References in corpus (12)

• Array Programming with NumPy
• TEMPO2, a new pulsar timing package. I: Overview
• Measurement of 21 cm brightness fluctuations at z ~ 0.8 in cross-correlation
• Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder
• A Method for 21cm Power Spectrum Estimation in the Presence of Foregrounds
• HI constraints from the cross-correlation of eBOSS galaxies and Green Bank Telescope intensity maps
• Detection of Cosmological 21 cm Emission with the Canadian Hydrogen Intensity Mapping Experiment
• The CHIME Pulsar Project: System Overview
• First Detection of Cosmic Structure in the 21-cm Intensity Field
• Holographic Beam Mapping of the CHIME Pathfinder Array
• Using the Sun to Measure the Primary Beam Response of the Canadian Hydrogen Intensity Mapping Experiment
• Gain and Polarization Properties of a Large Radio Telescope from Calculation and Measurement: The John A. Galt Telescope

Cited by in corpus (3)

• FAST Drift Scan Survey for HI Intensity Mapping. II. Stacking-based Beam Construction of the 19-feed Array at $1.4$ GHz
• Beam Maps of the Canadian Hydrogen Intensity Mapping Experiment (CHIME) Measured with a Drone
• Drone Beam Mapping of the TONE Radio Dish Array