Annu. Rev. Astron. Astrophys. 2001. 39: 249-307 Copyright © 2001 by Annual Reviews. All rights reserved

3.3. Background Measurements from IRAS

The Infrared Astronomical Satellite (IRAS) carried out the first all-sky survey in the infrared, mapping the sky at 12, 25, 60, and 100 µm (Neugebauer et al. 1984). The IRAS survey instrument measured the total sky brightness, although it was designed primarily for detection of discrete sources. It did not contain a cold shutter or other internal means to establish or monitor the instrumental zero point for the brightness measurements. Nevertheless, an approximate absolute brightness scale was determined (Beichman et al. 1988). The IRAS data clearly revealed large-scale, diffuse emission components of the sky brightness from the solar system and Galaxy (Hauser et al. 1984, Low et al. 1984; for a review, see Beichman 1987). Though several authors noted potential evidence for an extragalactic background component in the IRAS 100 µm data (Rowan-Robinson 1986, Rowan-Robinson et al. 1990, Boulanger & Pérault 1988), the uncertainties in the IRAS zero-point calibration and in the removal of foreground contributions precluded firm detection of the CIB in these studies.