Latest COBE Data Sets Ready

Volume 10, Numbers 3 & 4, December 1994
by Dave Leisawitz
The Cosmic Background Explorer (COBE) Project Data Sets are now publicly accessible from the NSSDC. The new data products augment their predecessors and include some calibration refinements. Specifically, the Project Data Sets provide all-sky, full spectral range Diffuse Infrared Background Experiment (DIRBE) and Far Infrared Absolute Spectrophotometer (FIRAS) coverage, DIRBE polarimetry, and the first two years of Differential Microwave Radiometer (DMR) data. Calibrated, time-ordered data are also available. The DMR project datasets were released in June 1994; the DIRBE and FIRAS project datasets were released in early October. Except for the time-ordered data, the DMR pixel-sorted data, and the DIRBE weekly sky maps, all of the files were made accessible from NSSDC's anonymous ftp site within a couple days of their receipt. CD-recordables containing the DMR pixel-sorted data and the DIRBE weekly sky maps were produced within a few weeks of the data delivery dates. Two more CD-recordables are planned, one replicating the DIRBE files kept online and another replicating the FIRAS files kept online, including a supplementary set of FIRAS files. All of the data, including the time-ordered data, are available on 8mm or 4mm tape. Like the initial products, most of the project datasets are presented in FITS binary tables.

Overviews of the new COBE data products are available either by anonymous ftp in the "cobe" directory at ( or on the World Wide Web's COBE home page at URL The latter is recommended if you have access to a Mosaic client. Click on "About the data products" or download the files dmr_pds_products.doc, dmr_asds_products.doc, dirbe_pds_products.doc, and firas_pds_products.doc from the COBE ftp directory. If there is sufficient interest in the scientific community and if funding permits, additional data products may be developed that would enhance the utility of the project datasets. For example, a set of zodiacal light-subtracted DIRBE maps would greatly facilitate analysis of extra-solar system sources of infrared emission.

In June 1993, an initial set of COBE data products was delivered to the NSSDC for public access. The Initial Products and accompanying documentation and images are now in the hands of more than a thousand researchers, educators, and other curious individuals. To date, 29 investigators have been funded or otherwise approved under NASA's Astrophysics Data Program as COBE Guest Investigators. Well over 100 others who lack such support have conducted serious research with the COBE data. More than 800 scientific papers now in the literature - ten times the number written by the instrument PIs or other members of the COBE Science Working Group - either present, interpret, or directly depend upon COBE results; indeed, it's unusual to find a cosmology paper that does not refer to COBE.

Launched November 18, 1989, the COBE satellite was developed by NASA's Goddard Space Flight Center to measure the diffuse infrared and microwave radiation from the early universe to the limits set by our astrophysical environment. The FIRAS instrument compares the spectrum of the cosmic microwave background radiation with a precise blackbody, the DMR maps the cosmic radiation precisely, and the DIRBE searches for the cosmic infrared background radiation.

To register your interest in additional data products or to request further assistance, please contact:

David Leisawitz
Astrophysics Data Facility, Code 631
NASA/GSFC  Greenbelt, MD 20771
voice: 301-286-0807
Please include the following statement in your publication acknowledgements: "The COBE datasets were developed by the NASA Goddard Space Flight Center under the guidance of the COBE Science Working Group and provided by the NSSDC."

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Author:Miranda Beall
Curators: Erin Gardner and Miranda Beall
Responsible Official: Dr. Joseph H. King, Code 633
Last Revised: 21 Nov 1996 [EDG]