Rocket measurement of the cosmic-background-radiation mm-wave spectrum

This paper reports the most precise constraint to date on the spectrum of the cosmic background radiation (CBR), obtained from measurements made with a liquid-helium-cooled spectrometer carried above the atmosphere on a rocket. The spectrum is very well fitted by a Planck function of temperature T = 2.736 K. The scatter of the equivalent temperature in the band 3-16/cm is + or - 10 mK, about 1/3 percent of the mean, whereas the estimated overall accuracy of the mean temperature is + or - 17 mK. These results are inconsistent with a previously reported excess IR intensity in the CBR but are in good agreement with COBE results reported by Mather et al. (1990). (Author)