Anisotropy in the Microwave Sky at 90 GHz: Results from Python II

We report on additional observations of degree-scale anisotropy at 90 GHz from the Amundsen-Scott South Pole Station in Antarctica. Observations during the first season with the Python instrument yielded a statistically significant sky signal with an amplitude of Delta T/T ~ 3.5 x 10-5 for a Gaussian autocorrelation function model with a coherence angle theta c = 1 deg. In this Letter we report the confirmation of that signal with data taken in the second year, and on results from an interleaving set of fields. Using the entire data set, we find Delta T/T = C^{1/2}₀ = 2.8^{+1.1}_{-0.7} x 10-5 for the Gaussian autocorrelation model mentioned above, and Delta T/T = [le(le + 1)Cl/(2 pi )]1/2 = 2.1^{+0.7}_{-0.5} x 10-5 for a band power estimate, where le = 93 is the effective center of our window function. The stated errors represent a 68% confidence interval in the likelihood added in quadrature with a 20% calibration uncertainty.