ACBAR, the Arcminute Cosmology Bolometer Array Receiver, is a 16 element, 300 mK bolometer array designed specifically for observations of CMB anisotropy and the SZE. It will operate in atmospheric windows spanning millimeter to submillimeter wavelengths; extending the spectral range over which observations of CMB anisotropies are made is necessary to separate CMB signals from foreground contamination. Multifrequency observations will make it possible to measure CMB anisotropies to l about 3000, determine galaxy cluster peculiar velocities via the kinetic SZE, and perform sensitive searches for distant galaxy clusters. To improve foreground removal, the beam sizes are matched at 4' for all four bands. Because of its stable atmosphere and extremely low water vapor, the South Pole is the best known terrestrial site from which to carry out this program of observations.

ACBAR is scheduled to be deployed on the Viper telescope and begin observations in December, 2000. The bolometers, filters, feed structures, cryostat, refrigerator read-out electronics, data aquisition system, tertiary mirror, cryostat mount and cabling are either complete or being fabricated (see Figures 4 and 5).

CARA's final year will be the first for ACBAR observing; we plan to acquire several months of integration during that austral winter, leading to our first results on the science goals mentioned above.


Since the telescope has not yet seen first light, there are no scientific results available.


See Figures 4 and 5.

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ACBAR is based in California at Univ Calif/Berkeley, Univ Calif/Santa Barbara, and CalTech. For more information, contact Bill Holzapfel,, or John Ruhl,