Published in "Extragalactic Background Radiation", Space Telescope Science Institute Symposium Series 7, 1995, eds. D. Calzetti, M. Livio and P. Madau
Abstract. The Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer (COBE) satellite is designed to conduct a sensitive search for isotropic cosmic infrared background radiation over the spectral range from 1.25 to 240 µm. The cumulative emissions of pregalactic, protogalactic, and evolving galactic systems are expected to be recorded in this background. The DIRBE instrument, a 10-spectral band absolute photometer with an 0.7° x 0.7° field of view, has mapped the full sky with high redundancy at solar elongation angles ranging from 64° to 124° to facilitate separation of interplanetary, Galactic, and extragalactic sources of emission. Initial sky maps show the expected character of the foreground emissions, with relative minima at wavelengths of 3.5 µm and longward of 100 µm. Conservative limits on the isotropic infrared background are given by the minimum observed sky brightness in each DIRBE spectral band. Extensive modeling of the foregrounds is required to isolate or strongly limit an extragalactic infrared component. The COBE Far Infrared Absolute Spectrophotometer (FIRAS) experiment has already established strong upper limits to any isotropic background from 500 µm to 5000 µm wavelength in excess of the 2.726 K blackbody radiation of the cosmic microwave background.
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