Comparing Redundant and Sky Model Based Interferometric Calibration: A First Look with Phase II of the MWA

Abstract

Interferometric arrays seeking to measure the 21 cm signal from the Epoch of Reionization must contend with overwhelmingly bright emission from foreground sources. Accurate recovery of the 21 cm signal will require precise calibration of the array, and several new avenues for calibration have been pursued in recent years, including methods using redundancy in the antenna configuration. The newly upgraded Phase II of Murchison Widefield Array (MWA) is the first interferometer that has large numbers of redundant baselines while retaining good instantaneous UV-coverage. This array therefore provides a unique opportunity to compare redundant calibration with sky-model based algorithms. In this paper, we present the first results from comparing both calibration approaches with MWA Phase II observations. For redundant calibration, we use the package OMNICAL, and produce sky-based calibration solutions with the analysis package Fast Holographic Deconvolution (FHD). There are three principal results. (1) We report the success of OMNICAL on observations of ORBComm satellites, showing substantial agreement between redundant visibility measurements after calibration. (2) We directly compare OMNICAL calibration solutions with those from FHD, and demonstrate these two different calibration schemes give extremely similar results. (3) We explore improved calibration by combining OMNICAL and FHD. We evaluate these combined methods using power spectrum techniques developed for EoR analysis and find evidence for marginal improvements mitigating artifacts in the power spectrum. These results are likely limited by signal-to-noise in the six hours of data used, but suggest future directions for combining these two calibration schemes.

20 pages, 11 figures. Accepted to ApJ

References in corpus (45)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• The Murchison Widefield Array: the Square Kilometre Array Precursor at low radio frequencies
• The GMRT 150 MHz All-sky Radio Survey: First Alternative Data Release TGSS ADR1
• 21cmFAST: A Fast, Semi-Numerical Simulation of the High-Redshift 21-cm Signal
• Hydrogen Epoch of Reionization Array (HERA)
• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• Reionization and Cosmology with 21 cm Fluctuations
• Bright Source Subtraction Requirements For Redshifted 21 cm Measurements
• A Per-Baseline, Delay-Spectrum Technique for Accessing the 21cm Cosmic Reionization Signature
• Science with the Murchison Widefield Array
• Four Fundamental Foreground Power Spectrum Shapes for 21 cm Cosmology Observations
• The Epoch of Reionization Window: I. Mathematical Formalism
• Imaging the Epoch of Reionization: limitations from foreground confusion and imaging algorithms
• A Sensitivity and Array-Configuration Study for Measuring the Power Spectrum of 21cm Emission from Reionization
• The impact of point source subtraction residuals on 21 cm Epoch of Reionization estimation
• Calibration Requirements for Detecting the 21 cm Epoch of Reionization Power Spectrum and Implications for the SKA
• Foreground Contamination in Interferometric Measurements of the Redshifted 21 cm Power Spectrum
• Opening the 21cm EoR Window: Measurements of Foreground Isolation with PAPER
• First Season MWA EoR Power Spectrum Results at Redshift 7
• A study of fundamental limitations to statistical detection of redshifted HI from the epoch of reionization
• The low-frequency environment of the Murchison Widefield Array: radio-frequency interference analysis and mitigation
• Foregrounds in Wide-Field Redshifted 21 cm Power Spectra
• Precision Calibration of Radio Interferometers Using Redundant Baselines
• CHIPS: The Cosmological HI Power Spectrum Estimator
• Empirical Covariance Modeling for 21 cm Power Spectrum Estimation: A Method Demonstration and New Limits from Early Murchison Widefield Array 128-Tile Data
• The Impact of Modeling Errors on Interferometer Calibration for 21 cm Power Spectra
• Systematic biases in low frequency radio interferometric data due to calibration: the LOFAR EoR case
• First Limits on the 21 cm Power Spectrum during the Epoch of X-ray heating
• Fast Holographic Deconvolution: a new technique for precision radio interferometry
• The Fundamental Multi-Baseline Mode-Mixing Foreground in 21 cm EoR Observations
• MITEoR: A Scalable Interferometer for Precision 21 cm Cosmology
• Calibration of Low-Frequency, Wide-Field Radio Interferometers Using Delay/Delay-Rate Filtering
• Redundant Array Configurations for 21 cm Cosmology
• The Murchison Widefield Array 21 cm Power Spectrum Analysis Methodology
• Fast gain calibration in radio astronomy using alternating direction implicit methods: Analysis and applications
• The Hydrogen Epoch of Reionization Array Dish I: Beam Pattern Measurements and Science Implications
• Spectral calibration requirements of radio interferometers for Epoch of Reionisation science with the SKA
• Measuring Phased-Array Antenna Beampatterns with High Dynamic Range for the Murchison Widefield Array using 137 MHz ORBCOMM Satellites
• Polarized Redundant-Baseline Calibration for 21 cm Cosmology Without Adding Spectral Structure
• A High Reliability Survey of Discrete Epoch of Reionization Foreground Sources in the MWA EoR0 Field
• Brute-Force Mapmaking with Compact Interferometers: A MITEoR Northern Sky Map from 128 MHz to 175 MHz
• A high resolution foreground model for the MWA EoR1 field: model and implications for EoR power spectrum analysis
• A new layout optimization technique for interferometric arrays, applied to the MWA
• Redundancy Calibration of Phased Array Stations
• Self-calibration of highly-redundant low-frequency arrays - initial results with HERA

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• The Phase II Murchison Widefield Array: Design Overview
• Data Analysis for Precision 21 cm Cosmology
• Deep multi-redshift limits on Epoch of Reionisation 21cm Power Spectra from Four Seasons of Murchison Widefield Array Observations
• First Results from HERA Phase I: Upper Limits on the Epoch of Reionization 21 cm Power Spectrum
• Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations
• First Season MWA Phase II EoR Power Spectrum Results at Redshift 7
• Fundamental Limitations on the Calibration of Redundant 21 cm Cosmology Instruments and Implications for HERA and the SKA
• Mitigating the Effects of Antenna-to-Antenna Variation on Redundant-Baseline Calibration for 21 cm Cosmology
• Redundant-Baseline Calibration of the Hydrogen Epoch of Reionization Array
• Absolute Calibration Strategies for the Hydrogen Epoch of Reionization Array and Their Impact on the 21 cm Power Spectrum
• Machine learning astrophysics from 21 cm lightcones: impact of network architectures and signal contamination
• The Bias and Uncertainty of Redundant and Sky-Based Calibration under Realistic Sky and Telescope Conditions
• Detailed study of ELAIS N1 field with the uGMRT -- II. Source Properties and Spectral Variation Of Foreground Power Spectrum from 300-500 MHz Observations
• A Unified Calibration Framework for 21 cm Cosmology
• Science with the Murchison Widefield Array: Phase I Results and Phase II Opportunities
• Patterns of primary beam non-redundancy in close-packed 21 cm array observations
• Gridded and direct Epoch of Reionisation bispectrum estimates using the Murchison Widefield Array
• Calibration and 21-cm Power Spectrum Estimation in the Presence of Antenna Beam Variations
• Quantifying Excess Power from Radio Frequency Interference in Epoch of Reionization Measurements
• Constraining Warm Dark Matter and Pop III stars with the Global 21-cm Signal
• The Impact of Beam Variations on Power Spectrum Estimation for 21-cm Cosmology I: Simulations of Foreground Contamination for HERA
• Observing the Reionization : Effect of Calibration and Position Errors on Realistic Observation Conditions
• Exploring the cosmic dawn and epoch of reionization with 21cm line
• A Bayesian approach to high fidelity interferometric calibration II: demonstration with simulated data
• Packed Ultra-wideband Mapping Array (PUMA): Astro2020 RFI Response
• The Role of the Instrumental Response in 21 cm EoR Power Spectrum Gridding Analyses
• SKA-Low Intensity Mapping Pathfinder Updates: Deeper 21 cm Power Spectrum Limits from Improved Analysis Frameworks
• Spectral modelling of Cygnus A between 110 and 250 MHz. Impact on the LOFAR 21-cm signal power spectrum
• Effects of model incompleteness on the drift-scan calibration of radio telescopes
• Delay-Weighted Calibration: Precision Calibration for 21 cm Cosmology with Resilience to Sky Model Error
• A Comparative Analysis To Deal With Missing Spectral Information Caused By RFI In Cosmological HI 21CM Observations
• Calibration Schemes with $\mathcal{O}(N\log N)$ Scaling for Large-N Radio Interferometers Built on a Regular Grid
• Ionospheric effect on the synthetic Epoch of Reionization observations with the SKA1-Low
• Forecasting 21-cm power spectrum sensitivity to dark Matter-baryon scattering
• Impact of Calibration and Position Errors on Astrophysical Parameters of the HI 21cm Signal
• Synthetic Observations with the Square Kilometre Array (SKA) -- development towards an end-to-end pipeline
• Exploring One-point Statistics in HERA Phase I Data: Effects of Foregrounds and Systematics on Measuring One-Point Statistics
• A Bayesian approach to high fidelity interferometric calibration I: mathematical formalism
• Removing systematics-induced 21-cm foreground residuals by cross-correlating filtered data
• The Correlation Calibration of PAPER-64 data