NGC 4631 is a challenging edge-on galaxy for small telescopes under light polluted skies. But the nicknames Herring Nebula and Whale Galaxy do trigger our imagination, as does the label Arp 281. Its visual magnitude of 9.2 together with its surface brightness of 13.3 explain the objectâ€™s pale appearance. The galaxy can be found halfway on the path from Gamma Comae Berenices to Alpha Canum Venaticorum. Look for a ghostly streak of light, like a smoke trail of a passing meteor. The galaxyâ€™s core looks a tad brighter and elongated in an E-W direction as well. The boundaries of this amazing edge-on galaxy are difficult to determine. A mag. 12 star can be seen near the northern edge of the galaxyâ€™s halo. NGC 4631â€™s distance is estimated at 23 million l-y.
Site : Bekkevoort, Belgium ( 51Â° N )
Date : April 19, 2009
Time : around 22.00 UT
Scope : Skywatcher 102/500mm achromatic refractor
Eyepiece : Baader Hyperion Zoom at 8mm
Magnification : 63x
Filter : none
Seeing : 3/5
Transp. : 4/5
Sky brightness : 19.87 magnitudes per square arc second near zenith (SQM reading).
Sketch Orientation: N up, W right.
Digital sketch made with Corel Paint Shop Pro X2, based on a raw pencil sketch.