C-BASS South is a 7.6-m Cassegrain telescope with two antennae donated by Telkom (South Africa). One was used for testing at Hartebeesthoek and the other relocated to Klerefontein.[2] It was commissioned at Hartebeesthoek Radio Astronomy Observatory and began survey observations in 2014 when it was deployed in the Karoo. The secondary mirrors on both telescopes were supported by cones of radio-transparent foam to minimize the contamination from ground pick up and to avoid scattering the incoming polarized radiation.[1][3] The C-BASS North telescope was retired in April 2015 after the initial observing phase was complete.[4] C-BASS South continues to operate as of 2019.
The southern C-BASS telescope in the final stages of commissioning in the Karoo.
The survey has mapped not only the intensity but also the orientation of the incoming electromagnetic waves (polarization) at every point on the sky with an angular resolution of 0.73 degrees. The angular resolution represents the smallest details that can be distinguished in the images. This has been the first survey to map the sky at a frequency of 5 GHz—low enough to be synchrotron radiation dominated but high enough to be relatively unaffected by Faraday rotation. At this frequency most of the signal comes from emissions from high-energy electrons spiralling around magnetic fields in the galaxy. This radiation is highly polarized and a major foreground distorting the Cosmic Microwave Background (CMB) signal.[5]
^"C-BASS Klerefontein". South African Radio Astronomy Observatory - SARAO. Retrieved 6 August 2023.
^ abKing, O.G.; et al. (2010). Holland, Wayne S; Zmuidzinas, Jonas (eds.). "The C-Band All-Sky Survey: Instrument design status and First-look data". Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V. 7741: 77411I. arXiv:1008.4082. Bibcode:2010SPIE.7741E..1IK. doi:10.1117/12.858011. S2CID118360085.