MWA survey opens new window into the low-frequency radio sky
The Murchison Widefield Array (MWA) radio telescope has completed observations for a 2-year observing program to survey the entire radio sky accessible to the MWA. The GaLactic and Extragalactic All-sky MWA (GLEAM) survey was designed to meet the observational requirements of over 30 individual science programs that aim to study a diverse range of astrophysical sources and phenomena ranging from the most distant known quasars to nearby gas and magnetic fields in our Milky Way galaxy.
The GLEAM survey covers the entire sky south of declination +25 degs, including the Galactic plane. Observations were performed with almost continuous frequency coverage between 73 and 231 MHz with 10 or 40 kHz frequency resolution. The broad frequency coverage and fine frequency resolution enables the data to be used for many scientific applications. As well as broad frequency coverage, the GLEAM survey is unique in being sensitive to radio emission from both compact and large diffuse radio sources up to tens of degrees in angular size. This capability is enabled by the many different length “baselines” (distances between all combinations of pairs of the MWA’s 128 antenna tiles) comprising the MWA.
The angular resolution of images in the mid frequency range (155 MHz) is approximately 2 arcmin, which is comparable to or better than other radio sky surveys covering a large part of the southern sky. This provides the opportunity for scientists to add new data to the study of known radio sources and to search for new or rare objects that do not appear in other radio surveys.
GLEAM will form a significant legacy dataset from the MWA, both in terms of the raw data (which can be re-processed by future scientists) and from the tabulated source catalogues that are being generated by processing the data now. Sky surveys are typically highly valuable scientific products and are often used for studies well beyond what the original proposers envisaged. GLEAM data products, including an extragalactic compact source catalogue and a catalogue of supernova remnants in the Galaxy, are in preparation and expected in the latter half of 2015.
R. B. Wayth, E. Lenc, M. E. Bell, J. R. Callingham et al. in PASA (2015) “GLEAM: The GaLactic and Extragalactic All-sky MWA survey”