Multi-epoch Low Radio Frequency Surveys of the Kepler K2 Mission Campaign Fields 3, 4, and 5 with the Murchison Widefield Array

Abstract

We present Murchison Widefield Array (MWA) monitoring of the Kepler K2 mission Fields 3, 4, and 5 at frequencies of 155 and 186 MHz, from observations contemporaneous with the K2 observations. This work follows from previous MWA and GMRT surveys of Field 1, with the current work benefiting from a range of improvements in the data processing and analysis. We continue to build a body of systematic low frequency blind surveys overlapping with transient/variable survey fields at other wavelengths, providing multi-wavelength data for object classes such as flare stars. From the current work, we detect no variable objects at a surface density above 2e-4 per square degree, at flux densities of ~500 mJy, and observation cadence of days to weeks, representing almost an order of magnitude decrease in measured upper limits compared to previous results in this part of observational parameter space. This continues to show that radio transients at metre and centimetre wavelengths are rare.