Flux Density Calibration of Radio Bursts Detected in the Sidelobes of the Canadian Hydrogen Intensity Mapping Experiment

Fengqiu Adam Dong; Meena Seth; Paul Scholz; Nina V. Gusinskaia; Kiyoshi W. Masui; Juan Mena-Parra; Daniele Michilli; Ari Polterovich; Ingrid Stairs

arXiv · 2609.21074

Flux Density Calibration of Radio Bursts Detected in the Sidelobes of the Canadian Hydrogen Intensity Mapping Experiment

Fengqiu Adam Dong·Meena Seth·Paul Scholz·Nina V. Gusinskaia·Kiyoshi W. Masui·Juan Mena-Parra·Daniele Michilli·Ari Polterovich·Ingrid Stairs

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Abstract

The Canadian Hydrogen Intensity Mapping Experiment/Fast Radio Burst (CHIME/FRB) instrument is a transient astrophysical burst survey that is discovering FRBs, pulsars, and long-period transients. As a transit telescope, the survey is most sensitive within 2 degrees of the meridian; however, CHIME/FRB can detect bright astrophysical bursts out to its horizon, at 10^-2 to 10^-3 of its peak sensitivity. In this study, we detail the flux density calibration procedure for these bursts detected in the CHIME sidelobes for both channelized voltage (baseband) and intensity data. We validate and estimate the calibration uncertainties by beamforming baseband data towards bright, steady sources in the sidelobes, comparing baseband and intensity flux density calibrations of the same astrophysical transients, and calibrating intensity flux densities for transiting steady sources. We are able to calibrate flux densities for declinations spanning -12 degrees to +59 degrees out to hour angles of 30 degrees, and out to 90 degrees in hour angle for declinations near that of Taurus A (Crab Nebula, declination of about +22 degrees). We conclude that uncertainties in the flux density calibration for transients in the CHIME sidelobes range from 20% to 42%, depending on the data used and the hour angle of the burst.

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Fengqiu Adam Dong, Meena Seth, Paul Scholz, Nina V. Gusinskaia, Kiyoshi W. Masui, Juan Mena-Parra, Daniele Michilli, Ari Polterovich, Ingrid Stairs. 2026-09-17. Flux Density Calibration of Radio Bursts Detected in the Sidelobes of the Canadian Hydrogen Intensity Mapping Experiment. https://arxiv.org/abs/2609.21074

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