Number 32 (Story #3), May 1, 1991 by Phillip F. Schewe and Ben Stein THE ASTRO OBSERVATORY , looking at the sky at seldom-glimpsed extreme-ultraviolet wavelengths, has detected many hot stars normally overshadowed by the more prevalent but cooler stars shining at optical wavelengths. Astro, carried on board the Space Shuttle last December, made the first ultraviolet picture of the Crab nebula and found previously undetected features inside the globular cluster Omega Centauri (Theodore P. Stecher, NASA Goddard, 301-286-8718). Astro's x-ray detector was used to detect iron in the Perseus cluster of galaxies and to record its spectrum; according to Peter Serlemitsos (NASA Goddard, 301-344-5255), the determination of the distance to Perseus (224 million light years) represents one of the first times x rays (rather than visible light) were used to compute a redshift. (Science News, 27 April 1991.)