This project will construct a new 5 GHz radio polarimeter and use it to conduct the C-Band All Sky Survey (C-BASS), a radio survey of the entire sky sensitive to total intensity and linear polarization, with minimal corruption by instrumental systematic effects. The northern part of the survey will use an existing 5.5-meter antenna at the Owens Valley Radio Observatory. A parallel southern survey will be conducted through a future, differently supported, project. The 5-GHz C-BASS survey will be the first survey of diffuse Galactic emission at a frequency low enough to be dominated by synchrotron radiation but high enough to be uncorrupted by Faraday rotation effects. Its primary science goal is to improve the accuracy with which Galactic foreground signals can be removed from maps of the polarization of the cosmic microwave background (CMB). It will thus provide critical support for future experiments to measure that polarization, which is expected to provide key information about the epoch of inflation. The survey will also yield new results about the interstellar medium, magnetic field, and radiation mechanisms, inside the Galaxy.
The resultant sky maps will be made freely available soon after the completion of the northern survey, and should be very useful for future mission planning. This survey starts a collaboration between Caltech, the Universities of Oxford and Manchester in the UK, and Rhodes University in South Africa, including student exchanges. The research team will be creating teaching tools based on archives from the Nova public television series, to bring the excitement and wonder of astrophysics and cosmology into the K-12 classroom.
