Measurement of Arcminute‐Scale Cosmic Microwave Background Anisotropy with the Berkeley‐Illinois‐Maryland Association Array

We report the results of our continued study of arcminute-scale anisotropy in the cosmic microwave background (CMB) with the Berkeley-Illinois-Maryland Association array. The survey consists of 10 independent fields selected for low infrared dust emission and lack of bright radio point sources. With observations from the Very Large Array at 4.8 GHz, we have identified point sources that could act as contaminants in estimates of the CMB power spectrum and have removed them in the analysis. Modeling the observed power spectrum with a single flat band power with an average multipole of l eff = 6864, we find Δ T = 14.2 μK at 68% confidence. The signal in the visibility data exceeds the expected contribution from instrumental noise with 96.5% confidence. We have also divided the data into two bins corresponding to different spatial resolutions in the power spectrum. We find Δ T 1 = 16.6 μK at 68% confidence for CMB flat band power described by an average multipole of l eff = 5237 and Δ T 2 < 26.5 μK at 95% confidence for l eff = 8748.