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CARA Science: Viper

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Summary

Viper, a 2.1 meter off-axis telescope optimized for CMB observations, was installed at the South Pole in January 1998. The optical design of Viper includes an electrically driven mirror which allows the Viper beam to be rapidly swept across the sky. The Viper beam sweeps several degrees without significant beam distortion and without large variation of telescope emission or ground emission pick-up. This large sweep ability, along with the exceptional stability of the South Pole atmosphere allow Viper to be used for observations that extend across several degrees.

During 2000 Viper will host a CMB polarization experiment. Observations of CMB polarization have the potential to reveal the initial source of the anisotropies created within the first fraction of a second of the universe. So far there is no detection of polarization of the CMB, but predictions of the polarization fraction are 1 to 10% polarization. If these levels are correct, then the instrument being built for Viper may have sufficient sensitivity to make a detection.

The ACBAR bolometer array will be deployed on Viper in November 2000 to extend Viper's CMB anisotropy and SZE observations to higher frequencies and smaller angular scales. The Viper telescope will also be used to make sensitive polarization observations with the SPARO bolometer array for the remainder of 1999, and for extended periods in future years.

Results

Viper is the first CMB telescope designed to observe through the Antarctic winter; it is about to finish its second successful winter of observing. Its major accomplishments to date are:

Constraints on the anistropy of the CMB over the range 180 < l < 600, across the critical first acoustic peak in the anisotopy power spectrum. The data from the first year, shown in Figure 2. received considerable attention as they indicated the presence of the first acoustic peak at a location consistent with a flat universe. Data from the second year may provide a factor of ten more sky coverage and thereby a factor of three lower uncertainties.
Detection of the Sunyaev-Zel'dovich effect (SZE) toward the nearby galaxy culuster Abell~3667 -- see Figure 3.

Pictures

For more information

The group has a website at http://cmbr.phys.cmu.edu/vip.html .

Viper is based at Carnegie-Mellon University. For more information, contact Jeff Peterson, jeff@cmbr.phys.cmu.edu . [an error occurred while processing this directive]