Michael Braukus
Headquarters, Washington, D.C.                                                
April 8, 1992
(Phone:  202/453-1549 ) 

Randee Exler
Goddard Space Flight Center, Greenbelt, Md.
(Phone:  301/286-8955 )


RELEASE:  92-47

COMPTON OBSERVATORY DETECTS ACTIVE GALAXIES

   NASA's Compton Gamma Ray Observatory has made the first 
detection of high-energy gamma rays from a class of active 
galaxies similar to quasars.  The observations, made by the 
Energetic Gamma Ray Experiment Telescope (EGRET), suggest that 
high-energy gamma radiation provides a substantial contribution 
to the objects' overall luminosity.   

   These active galaxies are called BL Lacertae objects, a type 
of "quasar-like" object that emits vast but varying amounts of 
energy.  The candidate objects are in the constellations Ursa 
Major, Pictor and Camelopardalis.  They are designated as MK 
421, 0537-441 and 0716+714, respectively.

   These new gamma-ray results support the hypothesis that BL 
Lacertae objects, like quasars, may be powered by supermassive 
black holes.  The detection of these high energy gamma rays 
also provides another piece of evidence suggesting their 
similarity to quasars and adds important new insight into 
understanding the nature of BL Lacertae objects.  

   The EGRET science team previously reported detection of high 
energy gamma rays from six quasars.  The most intense, called 
3C 279, registered a total high-energy gamma ray emission more 
than 10- to 100-million times that of the Milky Way galaxy.

   EGRET, one of four instruments aboard the Compton 
Observatory, was assembled in-house by the Goddard Space Flight 
Center, Greenbelt, Md.  The U.S. Principal Investigator for 
EGRET is Dr. Carl Fichtel of NASA's Goddard Space Flight 
Center.  


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   Co-principal investigators for EGRET are Dr. Carl Fichtel, 
of Goddard, and Dr. Klaus Pinkau, Max Planck Institute for 
Extraterrestrial Physics, Garching, Germany.  EGRET is the 
joint effort by scientists and engineers at Goddard; Stanford 
University, Calif.; Max Planck Institute and Grumman Aerospace 
Corp., Bethpage, N.Y.

   The second of NASA's Great Observatories, the Compton 
Observatory was launched April 5, 1991, by the Space Shuttle 
Atlantis to study high-energy radiation from space.  The 
Compton Observatory is managed and operated by Goddard for 
NASA's Office of Space Science and Applications, Washington, 
D.C.
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