http://www.rssboard.org/rss-specification 720 http://ecuip-xtf.lib.uchicago.edu/xtf/search?expand%3Dspectral-Type;f1-spectral-Type%3DOptical;f2-instrument%3DPalomar%2060-inch Results for your query: expand=spectral-Type;f1-spectral-Type=Optical;f2-instrument=Palomar 60-inch Thu, 01 Jan 1970 12:00:00 GMT http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/optical-crab/optical-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 optical wavelength. http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/optical-crab/optical-crab.dc.xml Thu, 01 Jan 1970 12:00:00 GMT