Spiral Galaxy NGC 2742 in Ursa Major

This is a 10 minute exposure with an ST-6 CCD camera thru Kopernik's 20-inch F/8.1 Ritchey Chretien Cassegrain telescope working at F/4.9. The focal length was reduced using a lens in front of the camera. This gives a larger field, but also reduces resolution. The field of view is about 9.5x12 arc minutes, with North at the top, and the image scale is about 2.2 arc seconds per pixel.

NGC 2742 is a spiral galaxy in the Constellation of Ursa Major that is seen at an angle of about 45 degrees. Based on the published red shift, (Hubble Constant of 62 Km/sec per Mpc) a rough distance estimate for NGC 2742 is 68 million light years, with a diameter of about 59,200 light years.

Quote from The Deep Sky Field Guide to Uranometria 2000:
"Small, bright nucleus; several filamentary, knotty arms."

Dreyer's description from the New General Catalog(NGC): "Considerably bright, considerably large, extended 90°, easily resolvable."

The bright star at the upper right is SAO 14765; at 7.7 magnitude, it is just a little too dim to be seen by the unaided eye. The cross shape in the image is an artifact called “diffraction spikes”. They are caused by the vanes (sometimes called a "spider") that hold the telescope’s secondary mirror.

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• NGC 2742
• Magnitude: 12.3
• Constellation: Ursa Major
• RA: 09h 07m 34.0s
• Dec: +60° 28' 46" Epoch 2000
• Size (mins): 3.0' x 1.5'
• Classification: SA(s)c: II
                          Spiral, S-shaped, (uncertain), Luminosity Class II
  
  

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George Normandin, KAS

March 10th, 2001