The Cosmic Microwave Background Spectrum from the FullCOBEFIRAS Data Set

We have refined the analysis of the data from the FIRAS (Far InfraRedAbsolute Spectrophotometer) on board the COBE (COsmic Background Explorer). TheFIRAS measures the difference between the cosmic microwave background and aprecise blackbody spectrum. We find new tighter upper limits on generaldeviations from a blackbody spectrum. The RMS deviations are less than 50 partsper million of the peak of the CMBR. For the Comptonization and chemicalpotential we find $|y| < 15\times10^{-6}$ and $|\mu| < 9\times10^{-5}$ (95\%CL). There are also refinements in the absolute temperature, 2.728 $\pm$ 0.004K (95\% CL), and dipole direction, $(\ell,b)=(264.14^\circ\pm0.30,48.26^\circ\pm0.30)$ (95\% CL), and amplitude, $3.372 \pm 0.007$ mK (95\% CL).All of these results agree with our previous publications.Comment: 32 pages, LaTeX+aasms package, 6 figures as separate PostScript file. Submitted to Ap.