New Measurements of the Cosmic Microwave Background atλ=3.2cm andλ=1.58cm-Evidence in Support of a Blackbody Spectrum

In an effort to delineate the spectrum of the cosmic blackbody radiation, we have made more accurate measurements of the intensity at wavelengths of 3.2 and 1.58 cm. The results, combined with that at $\lambda =8.56\mathrm{}$ mm reported in the preceding Letter, indicate that over this wavelength range the spectrum is that of a black body at ${2.68}_{-0.14\mathrm{}}$ ${}_{}{}^{+0.09\mathrm{}}{}_{}{}^{}\mathrm{°}\mathrm{K}$. In particular, a hot greybody spectrum does not fit the results.