February 20, 1996
The universe has spent billions of years making things that shine. On your birthday, we celebrate one of its quieter masterpieces.
ASCA X-Ray Observatory
Birthday · February 20, 1996
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APOD published February 20, 1996. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
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.