Data from the Cosmic Background Explorer (COBE)

Abstract

The COBE¹ satellite was developed by the NASA Goddard Space Flight Center to measure the diffuse infrared and microwave radiation from the early universe, to the limits set by our astrophysical environment. It was launched on November 18,1989 and carried three instruments, a Far Infrared Absolute Spectrophotometer (FIRAS) to compare the spectrum of the cosmic microwave background radiation with a precise blackbody, a Differential Microwave Radiometer (DMR) to map the cosmic radiation precisely, and a Diffuse Infrared Background Experiment (DIRBE) to search for the cosmic infrared background radiation. The cosmic microwave background spectrum was measured with a precision of 0.03% (Mather et al., 1994), the spectrum of the cosmic dipole was measured (Fixsen et al., 1994), the background was found to have intrinsic anisotropy for the first time, at a level of a part in 10⁵ (Smoot et al. , 1992 and Bennett et al , 1994a), and absolute sky brightness maps from 1.25 µm to 240 µm have been obtained to carry out the search for the cosmic infrared background (Hauser et al. , 1991). As planned, COBE ceased collecting science data on December 23, 1993. The instruments that required cryogenic cooling (DIRBE, at wavelengths longward of 3.5 µm, and FIRAS) previously had stopped operating when the supply of liquid helium was exhausted on 21 September 1990. A more complete description of COBE is given elsewhere (Boggess et al. , 1992).