AMATEUR SETI: A Trillion-Star Search GRAVITATIONAL WAVES: Three Chirps & Counting TEST REPORT: iOptron's AZ Mount Pro PAGE 38 PAGE 24 PAGE 60 THE ESSENTIAL GUIDE TO ASTRONOMY CASSINI'S SATURN Every Picture Tells a Story PAGE 16 The Mysterious Disappearance of Luna 2 PAGE 52 Observing: The Beneļ¬ts of Keeping a Log PAGE 32 Ethics in Astrophotography PAGE 66 SEPTEMBER 2017 Deep-Sky Wonders: Late Summer Double Stars PAGE 54 skyandtelescope.comhttp://www.skyandtelescope.com