M35 and NGC 2158 - Open Clusters in Gemini

M35 is a beautiful open cluster in the constellation Gemini. M35, which is shown above in the middle of the image, is a relatively young open cluster at 150 million years old, and relatively diffuse, with about 2,500 stars spread out over a volume 30 light years across. Because M35 is relatively young, it is comprised of mostly bright blue stars. The smaller cluster at the right, NGC 2158, is an older and much more compact open cluster. NGC 2158 is nearly four times more distant than M35 and over 10 times older. Most of NGC 2158's younger bright blue stars have self-destructed, leaving the cluster to be dominated by older and yellower stars as is readily apparent in the image above.

Image Specifications:

     •  Instrument:  Takahashi FS-102 Refractor (820mm - f/8) with 0.8x Televue reducer
     •  Camera:  Canon 20Da
     •  Filters:  Hutech IDAS LPS (Light Pollution)
     •  Mount:  Losmandy GM-8 Equatorial
     •  Guiding:  SBIG STV Autoguider with Vixen 400mm Guidescope
     •  Time / Date :  January 10, 2007, 10:00PM EST
     •  Location:  Coyle Field, NJ
     •  Weather:  Clear, 25degF
     •  Primary Exposure :  10 x 2min, ISO 1600, RAW, average combined
     •  Calibration Frames:  7 x 2min, ISO 1600, RAW, dark frames, no flats
     •  Image Processing :  Images Plus, Photoshop CS2