3-mm Anisotropy Measurement and the Quadrupole Component in the Cosmic Background Radiation

The large-scale anisotropy in the cosmic background radiation has been measured at 3-mm wavelength with a liquid-helium-cooled balloon-borne radiometer sensitive enough to detect the dipole in one gondola rotation (1 min). Statistical errors on the dipole and quadrupole components are below 0.1 mK with less than 0.1 mK galactic contribution. The authors find a dipole consistent with previous measurements but disagree with recent quadrupole reports. The measurement is also useful in the search for spectral distortions.