A short-wavelength measurement of the cosmic background radiation anisotropy

The results of a measurement of the cosmic microwave background (CMB) anisotropy at wavelengths between 0.4 and 2 mm, carried out using a balloon-borne 1.2 m telescope, are reported. A high Galactic latitude region about 15 deg wide with a 25 arcmin FWHM beam, switching in the sky with an amplitude of 108 arcmin, was observed. A sky signal correlated with the 100-micron diffuse emission mapped by the IRAS satellite was detected and used for calibration. After removal of this contribution, the residual intensity fluctuations give an upper limit to the anisotropy of the CMB at an equivalent frequency of 9.0/cm. 17 refs