The CHIME/FRB Outriggers: Commissioning the Hat Creek Outrigger and an Updated Calibration Scheme for Mitigating RFI
Abstract
This work presents commissioning of the Hat Creek Outrigger (HCO), a dual-polarization 256-element radio interferometer that is part of the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Outrigger project. Driven by a complex radio-frequency interference (RFI) environment that consistently contaminates ∼40% of HCO's usable bandwidth, we implement an improved calibration scheme using Gaussian Process Regression to recover complex gain solutions over RFI contaminated channels. To validate our method, we test the performance of the array using known transients and continuum sources over relevant timescales used for fast-transient research (≲ seconds). We find that our updated calibration scheme results in a ∼1.69× to 1.87× improvement in the array's point-source sensitivity, while simultaneously maintaining noise properties consistent with thermal statistics. As a result, we find that the array performs consistently within theoretical expectations across ≳80% of HCO's bandpass. We further observe an improvement in the interferometric performance after applying recently developed spatial filtering techniques for RFI mitigation, which rely on accurate calibration solutions for effective removal of unwanted interference. We conclude that our approach provides a valid framework for improving calibration solutions over RFI contaminated channels for large-N interferometric arrays more broadly. Our work motivates future development of more sophisticated techniques to recover astrophysical information in RFI-contaminated channels, departing from the historical practice of discarding them outright.
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BibTeX
@misc{lazda2026chimefrb,
title = {{The CHIME/FRB Outriggers: Commissioning the Hat Creek Outrigger and an Updated Calibration Scheme for Mitigating RFI}},
author = {Mattias Lazda and Nina V. Gusinskaia and Gurman Sachdeva and Shion Andrew and Juan Mena-Parra and Mandana Amiri and Bridget C. Andersen and Alyssa Atkinson and Kevin Bandura and Alice P. Curtin and Matt Dobbs and Ian Hendricksen and Jason W. T. Hessels and Danté M. Hewitt and Victoria M. Kaspi and Kholoud Khairy and Afrokk Khan and Ronniy C. Joseph and Adam E. Lanman and Calvin Leung and Kiyoshi W. Masui and Aaron B. Pearlman and Alexander W. Pollak and Vishwangi Shah and Kaitlyn Shin and Seth R. Siegel and Haochen Wang and Tarik J Zegmott},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.10686},
eprint = {2609.10686},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.10686},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The CHIME/FRB Outriggers: Commissioning the Hat Creek Outrigger and an Updated Calibration Scheme for Mitigating RFI
AU - Mattias Lazda
AU - Nina V. Gusinskaia
AU - Gurman Sachdeva
AU - Shion Andrew
AU - Juan Mena-Parra
AU - Mandana Amiri
AU - Bridget C. Andersen
AU - Alyssa Atkinson
AU - Kevin Bandura
AU - Alice P. Curtin
AU - Matt Dobbs
AU - Ian Hendricksen
AU - Jason W. T. Hessels
AU - Danté M. Hewitt
AU - Victoria M. Kaspi
AU - Kholoud Khairy
AU - Afrokk Khan
AU - Ronniy C. Joseph
AU - Adam E. Lanman
AU - Calvin Leung
AU - Kiyoshi W. Masui
AU - Aaron B. Pearlman
AU - Alexander W. Pollak
AU - Vishwangi Shah
AU - Kaitlyn Shin
AU - Seth R. Siegel
AU - Haochen Wang
AU - Tarik J Zegmott
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2609.10686
UR - https://arxiv.org/abs/2609.10686
AB - This work presents commissioning of the Hat Creek Outrigger (HCO), a dual-polarization 256-element radio interferometer that is part of the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Outrigger project. Driven by a complex radio-frequency interference (RFI) environment that consistently contaminates ∼40% of HCO's usable bandwidth, we implement an improved calibration scheme using Gaussian Process Regression to recover complex gain solutions over RFI contaminated channels. To validate our method, we test the performance of the array using known transients and continuum sources over relevant timescales used for fast-transient research (≲ seconds). We find that our updated calibration scheme results in a ∼1.69× to 1.87× improvement in the array's point-source sensitivity, while simultaneously maintaining noise properties consistent with thermal statistics. As a result, we find that the array performs consistently within theoretical expectations across ≳80% of HCO's bandpass. We further observe an improvement in the interferometric performance after applying recently developed spatial filtering techniques for RFI mitigation, which rely on accurate calibration solutions for effective removal of unwanted interference. We conclude that our approach provides a valid framework for improving calibration solutions over RFI contaminated channels for large-N interferometric arrays more broadly. Our work motivates future development of more sophisticated techniques to recover astrophysical information in RFI-contaminated channels, departing from the historical practice of discarding them outright.
ER -