Ian Heywood

Abstract:

The MeerKAT International GHz Tiered Extragalactic Exploration Survey (MIGHTEE) is one of the large survey projects using the MeerKAT telescope, covering four fields that have a wealth of ancillary data available. We present Data Release 1 of the MIGHTEE continuum survey, releasing total intensity images and catalogues over ∼20 deg2, across three fields at ∼1.2-1.3 GHz. This includes 4.2 deg2 over the Cosmic Evolution Survey (COSMOS) field, 14.4 deg2 over the XMM Large-Scale Structure (XMM-LSS) field and deeper imaging over 1.5 deg2 of the Extended Chandra Deep Field South (CDFS). We release images at both a lower resolution (7–9 arcsec) and higher resolution (∼5 arcsec). These images have central rms sensitivities of ∼1.3 −2.7 μJy beam−1 (∼1.2 −3.6 μJy beam−1) in the lower (higher) resolution images respectively. We also release catalogues comprised of ∼144 000 (∼114 000) sources using the lower (higher) resolution images. We compare the astrometry and flux-density calibration with the Early Science data in the COSMOS and XMM-LSS fields and previous radio observations in the CDFS field, finding broad agreement. Furthermore, we extend the source counts at the ∼10 μJy level to these larger areas (∼20 deg2) and, using the areal coverage of MIGHTEE we measure the sample variance for differing areas of sky. We find a typical sample variance of 10-20percnt for 0.3 and 0.5 sq. deg. sub-regions at S1.4 ≤ 200 μJy, which increases at brighter flux densities, given the lower source density and expected higher galaxy bias for these sources.

Abstract:

We have conducted observations of the nearby (11.46 ly) star system Procyon, using MeerKAT’s UHF (544–1087 MHz) receivers. We produce full-Stokes time and frequency integrated continuum images, as well as total intensity time series imaging at 8 s cadence, and full-Stokes vector-averaged dynamic spectra from the visibilities in order to search for transient activity such as flaring events. We detect no significant radio emission from the system, and estimate an upper limit on the circular polarization fraction of 65% (3σ confidence level). A comparison with previous Very Large Array observations places a 3σ lower limit on the spectral index between 815.5 and 8400 MHz of 0.26, however long-term significant variability over the last 33 yr cannot be ruled out without further, regular radio monitoring of the system.