M3 - Globular Cluster in Canes Venatici
An extremely dense cluster, rich in variable stars and Charles Messier's first "original" discovery in his list.


  • RA:13:42
  • Dec: 28:23
  • Size: 16.2'
  • Magnitude: 6.4
  • Distance: 30,600 ly
  • Constellation: Canes Venatici
  • Millennium Star Atlas: Vol. II, p. 651
  • Scope: 12.5" Ritchey-Chretien at f/9
  • Autoguider: ST-4 in faint mode
  • Sky conditions: Cold, relatively good seeing
  • Film: FLI DM CCD camera
  • Exposure: 9x90 seconds L, 6,7,7x120 seconds R,G,B
  • Date: 5-4-02

Out testing a few of Stan Moore's comments on optimizing exposure length versus camera readout noise. Just to make life a little more interesting, the ST-4 decided to develop a nice ice crystal on the optical window and generated a few spurious guiding artifacts and some major heartburn.


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