Cepheus

With a return to autumn, the temperatures have finally begun cooling in the southeast United States and the swarms of vampiric mosquitoes are thinning in numbers. After sleeping through this summer in my shed (and providing shelter to any number of spiders), the big dob I purchased last winter was ready to catch some photons. This past Monday on the night of the autumnal equinox, we shook off the webs, or in some cases beat them down with a stick, and rolled into the backyard to take on Cepheus, the Royal Father of Andromeda.

This constellation is generally much less bright than some of its late-summer/early fall counterparts. And from my backyard, still suffering slightly from the Alabama summer haze, it looks decidedly less regal and much more akin to a child's drawing of a house. Using my trusty Pocket Sky Atlas and the observing lists for the different Astronomical League clubs, I had already compiled a list of objects to observe. In originally sweeping over the constellation with my guide scope, the dearth of bright stars towards the constellation northern end (with a handful of exceptions) and the great number of stars at the base of the "throne" made it difficult for me to orient myself when switching between the guide scope and the eyepiece. A 12 inch scope can really fill the view up quick when skimming the edge of the Milky Way, which does not correspond to the view in the guide scope. Finally, I settled on a simple asterism located near the center of Cepheus as my home position for Star hopping. Just north and east of the open cluster NGC 7142 is a small collection of five stars that mimic the general shape of the larger constellation. This collection stood out in the finder scope easily due to its shape, and I could quickly return to it from one object to jump over to the next.

The first object I viewed is actually quite distant from the remaining objects, the planetary nebula NGC 40, which is located at the top (northern end) of the constellation, as viewed in the Pocket Star Atlas on page 71. For this objective, I started at the bright star Errai (Gamma Cepheus) and slowly followed a trail of magnitude 6 and 7 stars over to the nebula. My sketch, using a Hyperion 17 mm eyepiece with a 2x Barlow for a magnification of 176x shows a small compact halo around a visible, though faint central Star that seemed slightly off-center to West (Burnham's Celestial HandBook gives the magnitude of the central Star at 11.5). All of the remaining objects were viewed using the 17 mm Hyperion (88x) unless noted otherwise. Using the Orion ultrablock filter dimmed the surrounding field of faint stars but made the nebula appear more uniformly bright. I was pleased about this since I had been initially disappointed with the filter last winter.

Next, I jumped all the way across the constellation to one of the highlights of Cepheus, the open cluster/Galaxy duo of NGC 6939 and 6946. Like the planetary nebula I first viewed, actually used a different home position for Star hopping to these. The remainder of objects were observed jumping from the small collection of stars mentioned previously. For this pair, I centered on Alderamin, the brightest star in this constellation, and slid straight over to Eta Cepheus, from which it was a simple shift to NGC 6939 (PSA, page 73). This cluster appeared fairly compact at 88x, with a brighter Star immediately south and three similar stars outlining the other directions so that the cluster appears to be centered in a small cross. The brightest stars in this cluster appear on the western edge and fan out north and east and a progressively fainter pattern.

NGC 6946, also known as Caldwell 12, was just outside of the field of view Southwest of the cluster, on the opposite side of a bright star that centers the two. Initially, I could only detect the faintness brightening in this area to separate it from the sky glow, but after changing eyepieces to a 26 mm and 32 mm I could sketch a basic outline. I doublechecked my sketch against the photo in Burnham's later and had positioned correctly, but this was a difficult object for me. Galaxies between 10th and 11th magnitude (Burnham list this as 11th) generally give me trouble and take a bit of effort. In photographs this Galaxy shows nice spiral arms, but I would need much better conditions to be able to confirm those visually.

The next to objects I viewed are found back over on page 71 of the PSA, and both are fairly open clusters that did not contain a huge amount of stars. NGC 7160 was bright, and highlighted by two stars that stood out as a seemingly identical pair. The next cluster, NGC 7142, was just to the east of the small asterism I was using to Star hop from, but I was unable to confirm the nebula NGC 7129 nearby.

Moving over to what would be Cepheus' right foot, I located NGC 7380, and open cluster within a cloud of nebulosity. This object is found within a very rich star field, and my sketch reveals the general shape to be similar to a Chevron or arrow tip, with the nebulosity pointing Southwest. Again, the ultra block filter really helped to confirm the extent of the nebula.

From here, I shifted northwest to NGC 7510, another open cluster (enough with the open clusters already!) that turned out to be exceptionally small and concentrated in a wedge. The entire cluster is centered between three similar stars that form a roughly equilateral triangle. This completed all of the Herschel 400 items in this constellation (for those of you working on this monster list), but after having had my share of open clusters I decided to tackle some double stars as well. Delta Cepheus was easily split, and in a 26 mm with a Barlow appeared orange white with a somewhat fainter blue white companion. In my ignorance, I completely missed the significance of this system. Delta is a variable that was instrumental in determining that some "nebula" were actually Galaxies, and the predictability of Delta's change allowed astronomers to calculate (obviously I'm simplifying here, after all, math is not my strong suit) estimates that greatly enlarged our understanding of the size of the known universe. I just thought it was pretty.

Kurhah, a double in the center of the constellation, had much less separation than Delta, but when you're using a 12 inch telescope on a relatively clear night you can brute force that sucker apart. The difference in magnitude between the primary and secondary was also much greater.

The last double I viewed was Beta, also known as Alfirk, which had slightly more separation than the previous pair but an even greater difference in magnitude between the primary and secondary. The final object I viewed for the night was Herschel's Garnet Star, one of the most colorful (to a visual observer) stars in the sky. Its yellow orange appearance (Garnet maybe? Ha!) really stands out.

For a constellation I had never paid a lot of attention to, Cepheus held several interesting objects. And I'm now a handful of objects closer to completing the Herschel 400.