Michael Braukus
Headquarters, Washington, D.C.                                              
August 31, 1992
(Phone:  202/358-0872) 

Randee Exler
Goddard Space Flight Center, Greenbelt, Md.
(Phone:  301/286-7277)

Release:  92-138

NASA SATELLITE DETECTS NEW, EXTREME ULTRAVIOLET SOURCES 

   An object emitting extreme ultraviolet light located outside 
the Milky Way galaxy was detected by a NASA satellite through 
interstellar gas and dust, once thought to block this source of 
radiation.  This discovery assures that astronomers will have a 
new tool to probe the universe.  

   Also, EUVE has detected a new source of extreme ultraviolet 
radiation (EUV) from the corona of a star much like the sun, 
located about 16 light years from Earth.  A white dwarf 
companion star also appears in the photograph released today.

   On July 8 and 9, NASA's Extreme Ultraviolet Explorer (EUVE) 
measured an outburst from a "cataclysmic variable," a closely 
orbiting pair of stars in which gravitational forces pull matter 
from the outermost layers of a normal star onto the surface of a 
white dwarf companion.  The hot, compressed stellar material 
generates an explosive burst of extreme ultraviolet radiation as 
the material falls into the deep gravitational field of the 
white dwarf.

   Other explosive events are flares on stars.  These are 
unpredictable, giant versions of eruptions known to occur on a 
smaller scale on our own sun.  EUVE caught two such events on 
the red dwarf stars called AT Microscopium and AU Microscopium.

   Also, EUVE astronomers were surprised when they detected an 
object located outside our own Milky Way galaxy that was 
emitting extreme ultraviolet radiation (EUV).  At one time, 
astronomers had thought that the interstellar medium, the gas 
and dust spread throughout the galaxy, effectively would block 
their view of even nearby objects, because it is highly opaque 
to EUV radiation.
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   Each first view in a new spectral band gives astronomers a 
new tool to probe the universe.  The EUV window is one of the 
last unexplored spectral regions. 

   EUVE Principal Investigators Professor Stuart Bowyer and Dr. 
Roger Malina, of the University of California at Berkeley's 
Center for Extreme Ultraviolet Astrophysics (CEA), presented the 
findings today to space scientists at the World Space Congress 
in Washington, D.C.

   According to Professor Bowyer, initiator of the EUV program 
at Berkeley, "Years ago a lot of our colleagues thought we were 
crazy to observe in the EUV.  Everyone "knew" that trying to 
look through the interstellar medium at these wavelengths would 
be like trying to use a telescope in a San Francisco fog."

   Extreme ultraviolet (EUV) radiation is visible only to 
instruments above Earth's atmosphere.  Radiation at these 
energies is emitted by multi-million degree coronae on stars, by 
giant eruptions on novae, by the hot surfaces of white dwarfs 
and by other exotic sources in the cosmos. 

   The EUVE was launched June 7, 1992, to study the extreme 
ultraviolet, the part of the electromagnetic spectrum lying 
between optical and x-ray wavelengths.  It represents NASA's 
67th Explorer mission.  The first Explorer was launched on Jan. 
31, 1958, and it discovered the Van Allen radiation belts.

   The EUVE satellite, now 6 weeks into a survey of the entire 
sky, will provide astronomers with their first detailed maps in 
multiple EUV energy bands.

   Officials at NASA's Goddard Space Flight Center, Greenbelt, 
Md., report that the satellite has functioned smoothly since its 
launch.  All instruments are performing at or above expected 
levels, and data analysis is 50-percent ahead of schedule. 

   The EUVE Science Operations Center, based at CEA, operates 
around the clock, sending commands to point the instruments at 
selected astronomical sources and recording the findings of the 
satellite's four telescopes and three spectrometers.  The CEA 
has adopted a novel approach for operating the project with a 
staff that includes more than two dozen undergraduate students 
who are getting a unique hands-on educational experience. 

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   Researchers and engineers are studying the calibration and 
check-out data obtained during the first 6 weeks of the mission.  
These data serve a dual purpose.  They verify the instrument 
performance and at the same time, give astronomers valuable new 
measurements to test their models.

   NASA's Guest Observer Program begins at the conclusion of the 
6-month sky survey.  Scientists from around the world have 
applied to NASA to use the capabilities of the EUVE 
spectrometers.  Stiff competition will assure that only the very 
best of the 140 submitted proposals will result in allocated 
observing time.

   Goddard is responsible for the design, construction, 
integration, checkout and operation of EUVE.  The spacecraft's 
science instrumentation was designed, constructed and calibrated 
by the Space Science Laboratories of the University of 
California, Berkeley.  The EUVE is managed by Goddard for NASA's 
Office of Space Science and Applications, Washington, D.C.

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   Editors Note:  A photograph is available to media 
representatives by calling NASA's Broadcast And Imaging Branch 
on 202/453-8373.

     Color                            B&W
 92-HC-597                    92-H-653