COSMIC MICROWAVE BACKGROUND DIPOLE SPECTRUM MEASURED BY THE COBE FIRAS INSTRUMENT

The FIRAS instrument on the COBE has determined the dipole spectrum of the cosmic microwave background radiation (CMBR) from 2 to 20 cm(-1). For each frequency the signal is decomposed by fitting to a monopole, a dipole, and a Galactic template for similar to 60% of the sky. The overall dipole spectrum fits the derivative of a Planck function with an amplitude of 3.343+/-0.016 mK (95% confidence level), a temperature of 2.714+/-0.022 K (95% confidence level), and an rms deviation of 6x10(-9) ergs cm(-2) s(-1) sr(-1) cm limited by detector and cosmic-ray noise. The monopole temperature is consistent with that determined by direct measurement in the accompanying article by Mather et al.