Galaxies 20 Surveys 12 Cosmology 8 Geography 8 Stars 8 Galaxies active 7 History of science 6 Luminance 6 Radio astronomy 6 TK Electrical engineering. Electronics Nuclear engineering 6 human 6 Galaxy evolution 5 History of engineering and technology 5 Methods:statistical 5 Research & information: general 5 Technology: general issues 5 Astronomy, space & time 4 Black holes 4 Gravitation 4 Light pollution 4 Measurements of 4 NA Architecture 4 Photometry 4 Sloan Digital Sky Survey 4 T Technology (General) 4 article 4 galaxies: active 4 galaxies: evolution 4 methods: statistical 4 surveys 4