Don Savage
Headquarters, Washington, DC               February 28, 1996
(Phone:  202/358-1547)

Jim Sahli
Goddard Space Flight Center, Greenbelt, MD
(Phone:  301/286-0697)

RELEASE:  96-38

NASA RENAMES X-RAY TIMING EXPLORER IN HONOR OF BRUNO B. ROSSI

       NASA will name the X-ray Timing Explorer, placed into 
orbit in December 1995, in honor of a pioneer in the field of 
X-ray astronomy, Bruno B. Rossi.  The new official title of the 
6,700-pound observatory is the Bruno B. Rossi X-ray Timing 
Explorer (RXTE).

       The RXTE is currently in a circular 360-statute-mile 
(580-kilometer) orbit with an inclination of 23 degrees.  Among 
the objects to be studied by RXTE are stellar black holes, 
neutron stars and quasars.

         Professor Rossi and his colleagues discovered the 
first non-solar source of X-rays in a dramatic rocket flight in 
1962.  This source, Scorpius X-1, was the first of many 
collapsed stars that also are a key topic of study for the RXTE.

       Rossi, who died in 1993 after a long and distinguished 
career, served as professor of Physics and Professor Emeritus 
at the Massachusetts Institute of Technology.  He can be 
described as a pioneer in two separate fields of observational 
space astrophysics: X-ray astronomy and space plasma physics.  
He was the co-recipient of the prestigious Wolf Prize in 
Physics in 1987.  The Bruno Rossi Prize, awarded annually by 
the American Astronomical Society to a top astrophysicist for 
achievements in the field, is named in his honor.

       The spacecraft, which is about the size of a telephone 
booth, is carrying three science instruments which work together
to increase scientific understanding of cosmic X-rays sources.  

       Two of these instruments -- the Proportional Counter 
Array (PCA) and the High-Energy X-ray Timing Experiment (HEXTE) 
-- work in concert as the largest X-ray telescope yet flown, 
sensitive to X-rays from 2 to 200 keV.

       The third instrument, the All Sky Monitor (ASM), 
observes the long-term behavior of X-ray sources.  The ASM also 
serves as a sentinel which monitors the sky and enables the 
spacecraft to swing rapidly to targets of opportunity for the 
PCA and the HEXTE.  

        RXTE is the first mission for which 100 percent of the 
observing time will be available to the broad scientific 
community.  Specific observations will be proposed by 
scientists from the United States and abroad.  Observations are 
planned by scientists at the XTE Science Operations Center at 
NASA's Goddard Space Flight Center, Greenbelt, MD. 

       The RXTE was developed by and is managed and operated by 
Goddard for NASA's Office of Space Science, Washington, DC.