Eta Cas

β Cas
Beta Cassiopeia (Caph) is nearly as bright as alpha, at 2.28 visual magnitude. It's a delta Scuti variable, which means its fluctuations (2.25-2.31) are too small for naked eye appreciation; it's period is every 2 hours, 30 minutes.

In the same view, near the southern edge, is sigma, a five magnitude star with telescopic companion. The binary label is Struve 3049; it also has a second, fainter and wider companion:
      AB 5.0, 7.2; 326║, 2.5" (blue/yellow)
      AC 5.0, 10.4; 66║, 105.7".

You'll note the equally bright star just north of sigma, rho Cassiopeiae. Midway between the two stars is a globular cluster just visible in binoculars, and magnificent in larger telescopes: NGC 7789.

NGC 7789 is called Caroline's Rose; it was discovered by Caroline Herschel, the sister of William Herschel and an accomplished astronomer in her own right, eventually discovering eight comets as well as assisting her brother in his pursuits.

The open cluster is estimated to be 1.6 billion years old and many of its members are red giants, giving it a particular attraction.

Another open cluster is close byŚM52. Click on this object on the map for its details.

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ę 1999-2014 by Richard Dibon-Smith.