15, 17, 17P, 2007, 20D, ASTRONOMICAL, ASTRONOMY, ASTROPHOTOGRAPHY, BRIGHTENING, CANON, CHUMACK, COMA, COMET, COMETS, DECEMBER, EXPOSURE, HALO, HOLMES, IN, JOHN, MINUTE, NEWT, NIGHT, NUCLEUS, ON, OUTBURST, OUTER, PERIODIC, SKY, TELESCOPE, THRU, VIEWING,