http://www.rssboard.org/rss-specification 720 XTF Search Results (expand=spectral-Type;f1-spectral-Type=Optical;f2-instrument=Space Telescope Imaging Spectrograph) http://ecuip-xtf.lib.uchicago.edu/xtf/search?expand%3Dspectral-Type;f1-spectral-Type%3DOptical;f2-instrument%3DSpace%20Telescope%20Imaging%20Spectrograph Results for your query: expand=spectral-Type;f1-spectral-Type=Optical;f2-instrument=Space Telescope Imaging Spectrograph Thu, 01 Jan 1970 12:00:00 GMT Hubble Stays on Trail of Fading Gamma-Ray Burst Fireball, Results Point to Extragalactic Origin. http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/grb970228_hubble/grb970228_hubble.dc.xml It is difficult to determine the origin of a GRB, but sometimes it can be done. The visible light of this GRB was detected by ground-based telescopes, and once the light had faded a deep picture by the Hubble showed this GRB was located in a faint distant galaxy http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/grb970228_hubble/grb970228_hubble.dc.xml Fri, 05 Sep 1997 12:00:00 GMT