Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
February 20, 1996
ASCA X-Ray Observatory
Credit: ISAS, NASA
Explanation: Today marks the third anniversary of the launch of the Advanced Satellite for Cosmology and Astrophysics (ASCA; renamed from Astro D when launched). ASCA, seen here superposed on galaxy M31, is a Japanese satellite for which NASA has provided some scientific equipment. ASCA carries four large-area X-ray telescopes. At the focus of two of the telescopes is a Gas Imaging Spectrometer (GIS), while a Solid-state Imaging Spectrometer (SIS) is at the focus of the other two. ASCA has provided recent evidence that high energy cosmic rays are formed in the expanding gas from a supernova. During ASCA's three years of operation, it has also yielded valuable data on quasars, supernova remnants, dwarf novae, pulsars, clusters of galaxies, and the mysterious X-ray background radiation that appears to come from all directions.
Authors & editors:
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.