http://www.rssboard.org/rss-specification 720 http://ecuip-xtf.lib.uchicago.edu/xtf/search?expand%3Dsubject;f1-spectral-Type%3DX-ray;f2-subject%3DNebula Results for your query: expand=subject;f1-spectral-Type=X-ray;f2-subject=Nebula Thu, 01 Jan 1970 12:00:00 GMT http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/Xray-crab/Xray-crab.dc.xml The Crab Nebula, some 6,000 light years from Earth, is the remnant of a supernova explosion. It was seen on Earth in the year 1054. At the center of the bright nebula is a rapidly spinning neutron star, or pulsar, that emits pulses of radiation 30 times a second. This view shows the Crab in the X-ray wavelength. http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/Xray-crab/Xray-crab.dc.xml Sun, 29 Aug 1999 12:00:00 GMT