The W of Cassiopeia stands high in the northern sky these December nights and smack in the middle of the Milky Way. Any constellation crossed by that smoky stream of stars will find itself home to a rich assortment of star clusters and nebulae. Why? Our line of sight looks straight into the disk of the Milky Way Galaxy, where all the goodies are concentrated. We see a sampling of everything the galaxy has to offer from near to far.
Cassiopeia is absolutely loaded with clusters, some so bright, like the Double Cluster, you can see them with the naked eye. Many others require a small to modest telescope, from 3-inches to 6-inches, for a good view. A recent e-mail from my friend Chris Schur, an accomplished astrophotographer from Arizona, included a photo of a close-knit trio of star clusters we’ll nickname “The Triple Cluster.” All three are located within ½° (just one moon diameter) of the 4th magnitude star Kappa Cassiopeia near the center of the W, making them very easy to find. None are particularly bright however, so don’t expect to see them in binoculars or a wee department store telescope. You’ll need a 6-inch or larger telescope for a good view.
Start with low magnification — around 50x — and center Kappa in the field of view. Then look immediately northwest of the star (in the direction of the North Star) for three individual heaps or clumps of stars that are close enough together they comfortably fit in the same field of view: NGC 146, NGC 133 and King 14.
King 14 is the brightest at magnitude 8.5; the others are about 9th magnitude. Their small sizes and relative faintness has much to do with distance. NGC 146 lies nearly 10,000 light years away; NGC 133 around 2,000 light years and King 14 at 8,450 light years. All three stand out well from the rich background of field stars. King 14 and NGC 146 remind me of small pincushions stuck with shiny pins of different brightness. NGC 133 forms a distinctive line of a half dozen brighter stars peppered with fainter ones around and about.
With the moon rising later and later, these and other riches of the early winter sky stand ready to delight telescope users.