Related by context. Frequent words. (Click for all words.) 68 X ray emission 66 XMM Newton 66 optical telescopes 65 X ray Observatory 65 quasars 64 GRBs 64 galaxy clusters 63 NASA Chandra 63 astronomers 62 supernova remnant 62 gamma ray bursts 62 spectroscopic 61 gamma ray burst 61 distant galaxy 61 supernova explosion 61 galaxy cluster 61 supernovae 61 extrasolar planets 61 WM Keck Observatory 61 supernovas 60 astronomical observations 60 interferometry 60 pulsars 60 infrared telescope 60 magnetar 60 gravitational wave 60 distant galaxies 60 gravitational waves 60 spectrometers 60 COROT 60 planets orbiting 59 quasar 59 infrared wavelengths 59 gamma ray 59 spectrometer 59 redshift 59 telescope 59 HD #b [002] 59 neutron stars 59 cosmic microwave background 59 telescopes 59 galaxies 59 astrophysical 59 Very Large Array 59 globular clusters 59 Chandra X ray 58 supernova 58 ESO Very Large Telescope 58 extrasolar planet 58 exoplanets 58 WMAP 58 gravitational lensing 58 interferometer 58 planet orbiting 58 spectra 58 elliptical galaxies 58 Spitzer Space Telescope 58 Cassini 58 Very Large Telescope 58 comet nucleus 58 NASA Cassini spacecraft 57 THEMIS 57 orbiting telescope 57 terrestrial planets 57 Milky Way Galaxy 57 Space Telescope 57 Eta Carinae 57 Spectrometer 57 gamma rays 57 planets 57 substorms 57 optical telescope 57 Orion Nebula 57 pulsar 56 infrared spectrometer 56 cosmic ray 56 spectrograph 56 neutrino 56 brown dwarfs 56 dwarf galaxy 56 nebulae 56 Saturn rings 56 LIGO 56 cosmic rays 56 celestial objects 56 astrophysicists 56 interstellar dust 56 neutron star 56 Saturn moons 55 Hubble Space Telescope 55 super Earths 55 orbiting spacecraft 55 orbiting 55 rocky planets 55 Andromeda Galaxy 55 supernova explosions 55 Cassini Huygens 55 Cassini orbiter 55 observatories 55 ejecta 55 spectroscopy