Large-Scale Anisotropy in the 2.7-K Radiation with a Balloon-Borne Maser Radiometer at 24.5 GHz

Abstract

Observations with a high-sensitivity radiometer, covering 80% of the sky, give substantially improved measurements of anisotropy in the 2.7-K radiation. The dipole effect is $({T}_{x}, {T}_{y}, {T}_{z})=(\ensuremath{-}3.07\ifmmode\pm\else\textpm\fi{}0.17, 0.67\ifmmode\pm\else\textpm\fi{}0.09, \ensuremath{-}0.45\ifmmode\pm\else\textpm\fi{}0.09)$ mK; the Earth's orbital motion through the 2.7-K radiation is detected. No statistically significant quadrupole effect is seen, and a magnitude limit of 0.19 mK is established at the 90% confidence level. Covariance analysis for angular separations between 10\ifmmode^\circ\else\textdegree\fi{} and 180\ifmmode^\circ\else\textdegree\fi{} gives $〈\ensuremath{\delta}{T}_{1}\ensuremath{\delta}{T}_{2}〉<0.01$ ${(\mathrm{mK})}^{2}$.