Low Frequency Imaging of Fields at High Galactic Latitude with the Murchison Widefield Array 32-Element Prototype

Abstract

The Murchison Widefield Array (MWA) is a new low-frequency, wide field-of-view radio interferometer under development at the Murchison Radio-astronomy Observatory (MRO) in Western Australia. We have used a 32-element MWA prototype interferometer (MWA-32T) to observe two 50-degree diameter fields in the southern sky in the 110 MHz to 200 MHz band in order to evaluate the performance of the MWA-32T, to develop techniques for epoch of reionization experiments, and to make measurements of astronomical foregrounds. We developed a calibration and imaging pipeline for the MWA-32T, and used it to produce ~15' angular resolution maps of the two fields. We perform a blind source extraction using these confusion-limited images, and detect 655 sources at high significance with an additional 871 lower significance source candidates. We compare these sources with existing low-frequency radio surveys in order to assess the MWA-32T system performance, wide field analysis algorithms, and catalog quality. Our source catalog is found to agree well with existing low-frequency surveys in these regions of the sky and with statistical distributions of point sources derived from Northern Hemisphere surveys; it represents one of the deepest surveys to date of this sky field in the 110 MHz to 200 MHz band.

20 pages, 6 tables, 12 figures. 1 online-only machine readable table. Submitted to ApJ

References in corpus (15)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• The VLA Low-frequency Sky Survey
• The non-coplanar baselines effect in radio interferometry: The W-Projection algorithm
• Compact continuum source-finding for next generation radio surveys
• A lower limit of dz > 0.06 for the duration of the reionization epoch
• A Method for 21cm Power Spectrum Estimation in the Presence of Foregrounds
• Real-Time Calibration of the Murchison Widefield Array
• Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array
• An Improved Method for 21cm Foreground Removal
• The 74MHz System on the Very Large Array
• Non-parametric foreground subtraction for 21cm epoch of reionization experiments
• Deep Low-Frequency Radio Observations of the NOAO Bootes Field: I. Data Reduction and Catalog Construction
• First Spectroscopic Imaging Observations of the Sun at Low Radio Frequencies with the Murchison Widefield Array Prototype
• New 145-MHz Source Measurements by PAPER in the Southern Sky
• A new search for distant radio galaxies in the southern hemisphere - I. Sample definition and radio properties

Cited by in corpus (24)

• The Murchison Widefield Array: the Square Kilometre Array Precursor at low radio frequencies
• Reionization and the Cosmic Dawn with the Square Kilometre Array
• Overcoming real-world obstacles in 21 cm power spectrum estimation: A method demonstration and results from early Murchison Widefield Array data
• A study of fundamental limitations to statistical detection of redshifted HI from the epoch of reionization
• Initial deep LOFAR observations of Epoch of Reionization windows: I. The North Celestial Pole
• Empirical Covariance Modeling for 21 cm Power Spectrum Estimation: A Method Demonstration and New Limits from Early Murchison Widefield Array 128-Tile Data
• A 189 MHz, 2400 square degree polarization survey with the Murchison Widefield Array 32-element prototype
• The Importance of Wide-field Foreground Removal for 21 cm Cosmology: A Demonstration With Early MWA Epoch of Reionization Observations
• Foreground Model and Antenna Calibration Errors in the Measurement of the Sky-Averaged λ21 cm Signal at z~20
• The Effects of Polarized Foregrounds on 21cm Epoch of Reionization Power Spectrum Measurements
• A Fast Method for Power Spectrum and Foreground Analysis for 21 cm Cosmology
• A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz
• The Murchison Widefield Array Commissioning Survey: A Low-Frequency Catalogue of 14,110 Compact Radio Sources over 6,100 Square Degrees
• On the detection and tracking of space debris using the Murchison Widefield Array. I. Simulations and test observations demonstrate feasibility
• Mapmaking for Precision 21 cm Cosmology
• The first Murchison Widefield Array low frequency radio observations of cluster scale non-thermal emission: the case of Abell 3667
• Low Frequency Observations of the Moon with the Murchison Widefield Array
• The giant lobes of Centaurus A observed at 118 MHz with the Murchison Widefield Array
• A Flux Scale for Southern Hemisphere 21cm EoR Experiments
• Early Science with the Karoo Array Telescope: a Mini-Halo Candidate in Galaxy Cluster Abell 3667
• Murchison Widefield Array Observations of Anomalous Variability: A Serendipitous Night-time Detection of Interplanetary Scintillation
• Beamforming Errors in Murchison Widefield Array Phased Array Antennas and their effects on Epoch of Reionization Science
• The brightness and spatial distributions of terrestrial radio sources
• The precision and accuracy of early Epoch of Reionization foreground models: comparing MWA and PAPER 32-antenna source catalogs