A census of compact sources at 162MHz: first data release from the MWA Phase II IPS Survey

TL;DR

This paper presents a comprehensive catalogue of over 7000 compact radio sources at 162MHz detected via Interplanetary Scintillation, providing valuable data on source structure and flux density with the largest survey of its kind.

Contribution

It introduces the first data release from the MWA Phase II IPS survey, cataloguing compact sources across a large sky area with detailed scintillation measurements.

Findings

Detected 7839 sources with clear IPS signals

Over 85% of the surveyed area has a detection limit below 0.2 Jy

Reported NSI values for all detected sources and upper limits for many others

Abstract

We present a catalogue of over 7000 sources from the GLEAM survey which have significant structure on sub-arcsecond scales at 162MHz. The compact nature of these sources was detected and quantified via their Interplanetary Scintillation (IPS) signature, measured in interferometric images from the Murchison Widefield Array. The advantage of this approach is that all sufficiently compact sources across the survey area are included down to a well-defined flux density limit. The survey is based on $\sim$250$\times$ 10-minute observations, and the area covered is somewhat irregular, but the area within 1hr<RA<11hr; $-10^\circ<$Decl.$<+20^\circ$ is covered entirely, and over 85% of this area has a detection limit for compact structure below 0.2Jy. 7839 sources clearly showing IPS were detected ($>5\sigma$ confidence), with a further 5550 tentative ($>2\sigma$ confidence) detections. Normalised Scintillation Indices (NSI; a measure of the fraction of flux density coming from a compact component) are reported for these sources. Robust and informative upper limits on the NSI are reported for a further 31081 sources. This represents the largest survey of compact sources at radio frequencies ever undertaken.