http://www.rssboard.org/rss-specification 720 XTF Search Results (f1-subject=Observatory (space-based);f2-subject=Explorer 11) http://ecuip-xtf.lib.uchicago.edu/xtf/search?f1-subject%3DObservatory%20(space-based);f2-subject%3DExplorer%2011 Results for your query: f1-subject=Observatory (space-based);f2-subject=Explorer 11 Thu, 01 Jan 1970 12:00:00 GMT Artist’s Impression of the Explorer 11 in Orbit. http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/NASA-Explorer-11-Flight/NASA-Explorer-11-Flight.dc.xml Explorer 11, the first gamma-ray detection satellite flown, was launched on April 27, 1961. The satellite could not be actively pointed, so it was put into a tumble in order to get a "rough" scan of the entire celestial sphere.. http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/NASA-Explorer-11-Flight/NASA-Explorer-11-Flight.dc.xml Thu, 01 Jan 1970 12:00:00 GMT