http://www.rssboard.org/rss-specification 720 http://ecuip-xtf.lib.uchicago.edu/xtf/search?expand%3Dsubject;f1-subject%3DObservatory%20(space-based);f2-subject%3DHEAO-1%20All-Sky%20X-ray%20Catalog Results for your query: expand=subject;f1-subject=Observatory (space-based);f2-subject=HEAO-1 All-Sky X-ray Catalog Thu, 01 Jan 1970 12:00:00 GMT http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/greatobs_spectrum_300/greatobs_spectrum_300.dc.xml Because the Earth's atmosphere prevents certain types of radiation from reaching the ground, NASA proposed a series of Great Observatories designed to conduct space-based astronomical studies over many different wavelengths. The program launched four observatories: the Hubble Space Telescope (visible and near ultraviolet); Compton Gamma Ray Observatory (gamma rays); Chandra X-ray Observatory (soft X-rays); and Spitzer Space Telescope (infrared). Each observatory was designed to push the state of technology in its intended wavelength region. http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/greatobs_spectrum_300/greatobs_spectrum_300.dc.xml Thu, 01 Jan 1970 12:00:00 GMT