COBE Far Infrared Absolute Spectrophotometer observations of Galactic lines

The COBE Far Infrared Absolute Spectrophotometer (FIRAS) observations constitute an unbiased survey over the wavelength range from 100 mu m to 1 cm over 99% of the sky. Improved calibration of the FIRAS instrument and the inclusion of all of the FIRAS data allow an improved signal-to-noise ratio determination of the spectral lines by a factor of similar to 2 over our previous results. The resolution is low (0.45 cm(-1)), so only the strongest lines are observable. The CO chain from J = 1-0 to J = 8-7 is observed toward the Galactic center. The line ratios are roughly consistent with a 40 K excitation temperature. The 157.7 mu m C II and 205.3 mu m N II lines are observable over most of the sky. The 370.4 and 609.1 mu m lines of C I and the 121.9 mu m line of N II are observed in the Galactic plane. The line ratios at the Galactic center are consistent with a density of n(0) similar to 30 cm(-3) and a UV flux of G(0), approximate to 15 mu W m(-2) sr(-1) (10 Habing units). The 269 mu m H2O line is observed toward the Galactic center in absorption.