Measurement of the Cosmic-Background Large-Scale Anisotropy in the Millimetric Region

Dipole anisotropy in the cosmic background radiation in the 500-3000-μm wavelength region has been measured in a balloon-borne experiment. A dipole amplitude was found with $T_D=\left({2.9}_{-0.6\mathrm{}}^{+1.3\mathrm{}}\right)$ mK, at R. A. = 11h 24m±0h 40m, $\delta =3\mathrm{}°\pm 10°$, the errors arising essentially from detector and magnetometer calibrations. This Letter also reports the existence of a second harmonic $T_Q=\left({0.9}_{-0.2\mathrm{}}^{+0.4\mathrm{}}\right)$ mK.