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Abstract:

We present evidence for anomalous microwave emission in the RCW175 H II region. Motivated by 33 GHz 13′ resolution data from the Very Small Array (VSA), we observed RCW175 at 31 GHz with the Cosmic Background Imager (CBI) at a resolution of 4′. The region consists of two distinct components, G29.0-0.6 and G29.1-0.7, which are detected at high signal-to-noise ratio. The integrated flux density is 5.97 0.30 Jy at 31 GHz, in good agreement with the VSA. The 31 GHz flux density is 3.28 0.38 Jy (8.6σ) above the expected value from optically thin free-free emission based on lower frequency radio data and thermal dust constrained by IRAS and WMAP data. Conventional emission mechanisms such as optically thick emission from ultracompact H II regions cannot easily account for this excess. We interpret the excess as evidence for electric dipole emission from small spinning dust grains, which does provide an adequate fit to the data. © 2009. The American Astronomical Society. All rights reserved.

Abstract:

Digital beamforming for the aperture array components of the SKA poses considerable computational challenges. In this paper, we propose a hierarchical scheme aimed at tackling them and introduce OSKAR, a beamforming simulator which implements these ideas and algorithms.

Abstract:

The medium of RF signal transfer adopted for 2PAD was twisted pair differential signal cabling. While intended to demonstrate a low cost solution, the technique has brought with it several challenges, not least in terms of the losses and phase skew introduced. Some interesting engineering challenges have been faced along the way to delivering usable signals to the DSP Engineers. Faced with an aggressive RFI environment, with strong TV and GSM broadcast signals, a small, reasonably quiet band was exploited. A review of the RFI shielding policy has been required to maintain stability in the gain stages of the analogue system. An effective cabinet RFI barrier has been successfully demonstrated. Future work through PrepSKA will explore alternative cabling solutions, such as coaxial and optical fibre, with the intention of evaluating the main contenders against the cost, power, and performance requirements for SKA.