COBE Data Analysis Phase Ends, User Support Continues

Volume 13, Number 4, December 1997
By David Leisawitz

Results of the Cosmic Background Explorer (COBE) search for the cosmic infrared background will soon be presented in a series of Astrophysical Journal articles and talks to be delivered to an audience at the 191st meeting of the American Astronomical Society (AAS) in Washington, D.C. The latest results mark the culmination of work by the Diffuse Infrared Background Experiment (DIRBE) team to calibrate and analyze their data, model the Galactic and interplanetary infrared foreground emissions, estimate all the errors associated with the data and the models, and seek evidence for a residual, isotropic signal. Redshifted starlight and thermal emission from dust in early generations of galaxies are expected to produce the long-sought cosmic infrared background.

DIRBE all-sky image of the galactic plane at 1.25, 2.2, 3.5 micron.

Previous COBE results will be familiar to many readers. They include a precise measurement of the spectrum of the cosmic microwave background (CMB) from the Far-Infrared Absolute Spectrophotometer (FIRAS) and the discovery with the Differential Microwave Radiometers (DMR) of predicted spatial anisotropy in the CMB.

The final DIRBE data products include zodiacal emission subtracted maps of the infrared sky brightness in ten wavelength bands covering a spectral range from 1.25 to 240 microns. New FIRAS data products include recalibrated spectra and spectral line emission maps. These data were recently delivered to the NSSDC and will soon be accessible from a significantly expanded FTP archive. Apart from their unique value in cosmological studies, the COBE data will be used for years to come in Galactic and Solar System research.

Ever since the first COBE data were made publicly available in 1993, the Astrophysics Data Facility, NSSDC's partner at Goddard, has supported COBE Guest Investigators (GI) and provided on-line access to the data, analysis software, and documentation. Since the GI program's inception about a quarter of all the successful Astrophysics Data Program (ADP) proposals have come from prospective COBE data analysts. In addition to the ADP-funded researchers hundreds of scientists, book authors, students, and curious non-scientists have received personal responses to their COBE-related questions and downloaded files from the COBE Web site. The questions continue to pour in. The Astrophysics Data Facility will continue to provide support.

Yes, the DIRBE team did detect the cosmic infrared background at 140 and 240 micron wavelengths. Upper limits were placed on the CIB brightness at eight other DIRBE wavelengths ranging from 1.25 to 100 microns. The press release can be found at

For more information about COBE, its legacy as recorded in the literature, and access to COBE instructional materials, browsing tools, analysis software, and data products, please see the COBE Web site at or contact Dr. David Leisawitz at Dr. Janet Weiland was available to answer questions about the COBE data, new browsing tools, and analysis software at the Astrophysics Data Facility's exhibit booth at the AAS meeting.

The COBE satellite.

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Miranda Beall,, (301) 286-0162
Raytheon STX, Code 633, NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.

Erin D. Gardner,, (301) 286-0163
Raytheon STX, Code 633, NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.

NASA home page GSFC home page GSFC organizational page

Author:Miranda Beall
Curators: Erin Gardner and Miranda Beall
Responsible Official: Dr. Joseph H. King, Code 633
Last Revised: 26 JAN 98 [EDG]