We have refined the analysis of the data from the FIRAS ( Far InfraRed Absolute Spectrophotometer ) on board the COBE ( COsmic Background Explorer ) .
The FIRAS measures the difference between the cosmic microwave background and a precise blackbody spectrum .
We find new tighter upper limits on general deviations from a blackbody spectrum .
The RMS deviations are less than 50 parts per million of the peak of the CMBR .
For the Comptonization and chemical potential we find |y| < 15 \times 10 ^ { -6 } and | \mu| < 9 \times 10 ^ { -5 } ( 95 % CL ) .
There are also refinements in the absolute temperature , 2.728 \pm 0.004 K ( 95 % CL ) , and dipole direction , ( \ell,b ) = ( 264.14 ^ { \circ } \pm 0.30 , 48.26 ^ { \circ } \pm 0.30 ) ( 95 % CL ) , and amplitude , 3.372 \pm 0.007 mK ( 95 % CL ) .
All of these results agree with our previous publications .