``Limits on Arcminute-Scale Cosmic Microwave Background Anisotropy at 28.5 GHz''
We have used the Berkeley-Illinois-Maryland Association (BIMA)
millimeter array outfitted with sensitive centimeter-wave receivers to
search for cosmic microwave background (CMB) anisotropies on arcminute
scales. The interferometer was placed in a compact configuration that
produces high brightness sensitivity, while providing discrimination
against point sources. Operating at a frequency of 28.5 GHz, the FWHM
primary beam of the instrument is ~6&farcm;6. We have made sensitive
images of seven fields, four of which where chosen specifically to
have low IR dust contrast and to be free of bright radio sources.
Additional observations with the Owens Valley Radio Observatory (OVRO)
millimeter array were used to assist in the location and removal of
radio point sources. Applying a Bayesian analysis to the raw
visibility data, we place limits on CMB anisotropy flat-band power of
Qflat=5.6+3.0-5.6 μK and Qflat<14.1 μK at 68% and 95%
confidence, respectively. The sensitivity of this experiment to
flat-band power peaks at a multipole of l=5470, which corresponds to
an angular scale of ~2'. The most likely value of Qflat is similar to
the level of the expected secondary anisotropies.