New 145-MHz Source Measurements by PAPER in the Southern Sky

TL;DR

This paper presents new 145-MHz sky measurements from PAPER in South Africa, mapping large sky regions with high sensitivity, establishing flux scales, and comparing source fluxes to existing catalogs to aid cosmic reionization studies.

Contribution

First large-scale 145-MHz sky map from PAPER with flux calibration and catalog comparisons for reionization foreground modeling.

Findings

Mapped 4800 square degrees with 0.7 Jy RMS sensitivity

Established flux scale consistent with existing catalogs

Provided new flux measurements for numerous sources at 145 MHz

Abstract

We present observations from the Precision Array for Probing the Epoch of Reionization (PAPER) in South Africa, observed in May and September 2010. Using two nights of drift scanning with PAPER's 60\arcdeg\ FWHM beam we have made a map covering the entire sky below +10 degrees declination with an effective center frequency of 145 MHz, a 70-MHz bandwidth, and a resolution of 26\arcmin. A 4800 square-degree region of this large map with the lowest Galactic emission reaches an RMS of 0.7 Jy. We establish an absolute flux scale using sources from the 160-MHz Culgoora catalog. Using the 408-MHz Molonglo Reference Catalog (MRC) as a finding survey, we identify counterparts to 480 sources in our maps, and compare our fluxes to the MRC and to 332 sources in the Culgoora catalog. For both catalogs, the ratio of PAPER to catalog flux averages to 1, with a standard deviation of 50%. This measured variation is consistent with comparisons between independent catalogs observed at different bands. The PAPER data represent new 145-MHz flux measurements for a large number of sources in the band expected to encompass cosmic reionization, and represents a significant step toward establishing a model for removing foregrounds to the reionization signal.