Roaming the Deep Sky #7
A Trio of Open Clusters in Cassiopeia
By Don Clouse
There are a number of places in the sky where multiple open clusters can be seen in the same telescopic field of view. Typically these will be wide field panoramas such as the Sword of Orion (NGC1981, NGC1977, NGC1980, M42 and more – see RDS #1) and M46, M47, and NGC2423 in Puppis. These groupings are rather dazzling in wide field instruments (2 degrees minimum, 2.5 to 3 is better) on dark, transparent nights. Less dazzling, but much smaller is a trio of open clusters in Cassiopeia: King 14, NGC133, and NGC146.
This grouping is no more than 20’ wide. I used a 24mm eyepiece (with a 51 degree apparent field) with my f/10 (2032mm focal length, 203mm aperture) Schmidt-Cassegrain (a Celestron Celestar 8) for the observations described here. This combo yields 85x magnification with a true field of view of 36 minutes of arc. Thus the 36’ true field of view comfortably encompassed all three clusters. These observations were done just after full darkness on Thursday, October 7, 1999 at the 10th Annual Twin Lakes Star Party. (This event is held each October on the grounds of the Golden Pond Observatory, Land Between the Lakes State Park, Kentucky.) Here are my descriptions, each of which begin with a listing of catalog data in the format: magnitude, size, Trumpler Classification, and number of stars.
- King 14 – 8.5, 7’, 3 2 p, 20* - This scattered, irregularly shaped cluster contains about a dozen stars of varying brightness in a 12’x8’ area.
- NGC133 – 9.4, 7’, 4 1 p, 5* - The four brightest stars are arranged three in a north-south line and one just off line. Another 5 or 6 fainter stars are visible in an area of about 4’x2’
- NGC146 – 9.1, 6’, 4 3 p, 20* - Twelve stars are directly visible, with averted vision yielding up another half dozen. Three faint pairs are included. The total size of the cluster is about 10’x4’.
The chart shows the three clusters along with 15 Cas (Kappa Cassiopeiae), a magnitude 4.2, spectral class B0 star. This group is surrounded by a circle representing a 36’ field of view. Stars down to 13th magnitude are shown. This chart may be useful in picking these clusters out from the surrounding star field. These clusters are fairly easily located, since Kappa Cas is easily visible to the unaided eye and quite near the trio. Any star chart will show the location of Kappa Cas, north of the western side of the distinctive Cassiopeia "W" shape. Just center Kappa Cas in your finder and put in your lowest power eyepiece. Move Kappa Cas to the southeast edge of the field. The three clusters should be present in the center to north side of the field depending on your true field size.
If you observe these clusters, you may find it of interest to keep the context of these objects in mind. Although, I could not find a distance for NGC133, the other two clusters are quite distant (with NGC133 perhaps being at a roughly equivalent distance). King 14 is in the vicinity of 9,000 light years away, a distance similar to that of the prominent "nearby" open clusters M103 and NGC457, also in Cassiopeia. NGC146 is a bit further away at more than 10,000 light years. That kind of distance places these clusters on the far side of the Perseus Spiral Arm of our galaxy. The Perseus Arm is the next spiral arm (or perhaps partial arm) out from our Local Spiral Arm, in a direction away from the center of our galaxy, the Milky Way Galaxy – a very large barred-spiral galaxy that counts our Sun among its 200 billion stars.
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