OBSERVING: Small Scope, Winter Sky PAGE 22 WHEN THE CALL COMES: Chasing Cosmic Flashes PAGE 36 IMAGING: Photograph Dark Nebulae PAGE 60 THE E S SENTIAL GUIDE TO ASTRONOMY DECEMBER 2021 DAVA SOBEL ON THE LIFE OF Henrietta Swan Leavitt Page 12 See Comet Leonard at Dawn Page 48 skyandtelescope.org Tips for Sidewalk Astronomy Page 84http://www.skyandtelescope.org