1998/10/28 by D. J. Fixsen, C. L. Bennett, Fixsen, D. J. +4
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9810466
12 pages, 5 Postscript Figures, uses aaspp4.sty, minor revisions to conform to the version accepted by ApJ
openalex publication_date 1998/10/28 · arxiv created 1999/01/25 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The COBE Far InfraRed Absolute Spectrophotometer (FIRAS) observations constitute an unbiased survey over the wavelength range from 100 um 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 determination of the spectral lines by a factor of ~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 towards the Galactic center. The line ratios are roughly consistent with a 40 K excitation temperature. The 157.7 um C II and 205.3 um N II lines are observable over most of the sky. The 370.4 um and 609.1 um lines of C I, and the 121.9 um line of N II are observed in the Galactic plane. The line ratios at the Galactic center are consistent with a density of n0 ~30 cm-3 and a UV flux of G0 ~15 uW m-2 sr-1 (10 Habing units). The 269 um H2O line is observed toward the Galactic center in absorption.