Paula Cleggett-Haleim
Headquarters, Washington, D.C.                                                    
August 10, 1993
(Phone:  202/358-0883)

Michael Finneran
Goddard Space Flight Center, Greenbelt, Md.
(Phone:  301/286-5565)


RELEASE:  93-145

COBE "BIG BANG" DATA MADE AVAILABLE TO SCIENTIFIC COMMUNITY

      Researchers from around the world now have access to data 
from the NASA satellite that provided the scientific community 
with an unprecedented look at how the universe began.

      "There are many theories of the early universe that can be 
tested with our data," said Dr. John Mather, Project Scientist for 
the Cosmic Background Explorer (COBE) at NASA's Goddard Space 
Flight Center, Greenbelt, Md., which built and manages the 
Earth-orbiting observatory.

      The first data sets from COBE were delivered the third week 
in July to the National Space Science Data Center at Goddard, from 
which scientists can access the data over computer networks.  More 
data sets are expected to be delivered. 

      In essence, the satellite, launched in November 1989, has 
peered back in time to detect the now faint whispers of the Big 
Bang that is widely believed to have started the expansion of the 
universe about 15 billion years ago.

      "What we've done is to measure the microwave radiation that 
comes to us almost equally from every direction and that is 
thought to be the primary remnant of the Big Bang," Mather said.

      COBE's first test of the Big Bang theory verified that the 
spectrum of the radiation agreed with predictions.  The second 
test discovered the predicted hot and cold spots in the Big Bang 
radiation, the telltale sign of lumpiness in the primordial 
universe.

      As the universe aged, the lumps condensed into the 
structures --  galaxies and clusters of galaxies, stars and 
planets -- that  abound today.  The space surrounding the 
primordial lumps evolved into the giant empty holes or "voids" 
found in the present-day arrangement of galaxies.
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      The same data that can be used to pursue the mission's 
cosmological objectives also provide information about the local 
universe, including the Earth's own Milky Way galaxy and the solar 
system.

      "The dust, molecules and atoms in the plane of our own 
galaxy, as well as stars, are all of great interest to people who 
are concerned about how stars and planets are formed and 
basically, how we got here," Mather said.

      "We've measured the pattern of dark and bright spots of the 
microwave radiation in the sky, and some theories make specific 
kinds of predictions about those spots," he added.  "Also, we've 
measured the spectrum of the radiation, which is the intensity at 
every wavelength, and some theories predict that this might not be 
exactly the way we see it.  So those also can be tested."

      The data, which come from the three instruments aboard COBE, 
are digital images of the sky as it appears at infrared and 
microwave wavelengths.  The data sets available for analysis 
include full sky maps from the first year of operation of COBE's 
Differential Microwave Radiometers (DMR) and data covering the 
galactic plane from the Diffuse Infrared Background Experiment 
(DIRBE) and the high-frequency channel of the Far Infrared 
Absolute Spectrophotometer (FIRAS).

      The DIRBE measurements were made in 10 infrared wavelengths 
ranging from 1.25 to 240 micrometers.  The FIRAS high-frequency 
channel covers the wavelength range 105 to 500 micrometers.

Data Center One of World's Largest

      The facility storing this data - Goddard's National Space 
Science Data Center - is one of the largest of its kind in the 
world.  The center is a clearinghouse for astrophysics and space 
science data and is linked to similar facilities around the globe 
for the sharing and disemination of information.  The center 
accepts data not only from Goddard, but from other NASA facilities 
and outside organizations.
  
      Additional data products are planned for delivery in June 
1994, including full-sky maps for all experiments and all 
wavelength bands, data from the second year of the DMR operation 
and time-ordered data.

      Interested users may contact David Leisawitz at Goddard's 
Astrophysics Data Facility at 301/286-0807 or by electronic mail 
at the Internet address leisawitz@stars.gsfc.nasa.gov.

      In addition, a guest investigator program has been 
established at the Cosmology Data Analysis Center near Goddard, 
where researchers selected by NASA Headquarters can gain expertise 
on how to work with the data and perform their analyses.

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