Some Preliminary Science Results

Preliminary Sky Maps

The northern C-BASS survey from OVRO is in progress. The maps presented below were made from data taken in August 2013. We are working on improving data checking (removing bad data corrupted by RFI, pointing errors, or contamination by the Sun), improving the procedures used to remove residual ground emission, and calibration. Further observations are in progress to improve sensitivity and reduce systematic errors in polarization. The maps show the full sky with the Galactic Center (not visible from the north) in the center. The grey region will be filled in by the southern survey. These maps are not ready for quantitative use!

Total Intensity. Solar contamination is visible in the upper right; this will be removed from the final maps.

Total intensity image

Polarized intensity. Spurious features due to the Sun and to incomplete destriping remain in this map, along with polarization leakage around bright sources.

Polarized intensity image

North Celestial Pole (NCP) Survey

As part of his Ph.D. research, Matthew Stevenson made a survey of the NCP region, using observations taken during the day when the Sun would contaminate the main survey. The observations were taken in total intensity only during a 6-month period in 2011-2012. They survey spans a 7-deg radius circle (150 sq deg), scanned in azimuth at 1 deg/s. Calibration was based on cross-scans of Cyg A, Tau A, and Cas A. Null-tests were used to find and eliminate bad scans, contaminated by RFI or other problems. The map support the hypothesis that spinning-dust emission (AME) is significant in this region at higher frequencies; it is inconsistent wth flat-spectrum synchrotron emission. A paper on these results is in preparation.

C-BASS NCP map Comparison Comparison

Last modified: Sun Nov 10 15:38:28 PST 2013