Spiral galaxy M91 = NGC 4548

This CCD image shows the bright spiral galaxy M91 (NGC 4548) in Virgo. It is notable for its central bar and for the intricate detail of star-forming regions and dust in its spiral arms.

This image is from a 5-minute blue-light exposure taken during twilight with a Tektronix 2048x2048 CCD at the 2.1-meter telescope of Kitt Peak National Observatory, by Bill Keel and Lisa Frattare. North is at the top and east to the left, for direct comparison with a chart or eyepiece view. The image has been block-averaged by a factor of 2, another factor of two as shown above (click for full size). I used a logarithmic intensity transformation to preserve information across a wide dynamic range. The field is 9.3 arcminutes high.

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Last changes: 7/2003      © 2003