Sunday, October 23, 2011

Summer and fall objects

While waiting for nights without a bright moon to drown out faint objects, I was observing brighter objects such as double and multiple stars, Jupiter and bright nebulae and star clusters from home. And when the night wore on, the moon too even though it's dazzling through the 15-inch. I have been looking at objects principally along the summer Milky Way from Aquila and Scutum to the south to Cassiopeia and Perseus to the north. Among them were the planetary nebulae M-57 and M-27, which are bright enough to be impressive even from my light polluted front yard in the middle of a brightly lit up suburb. I also observed other planetary nebulae such as NGC-6210, NGC-6826 and NGC-6891. Others objects I looked over were the globular clusters M-13, M-92, M-15, M-2, M-30, M-71, NGC-7006, NGC-6934 and NGC-6229. All of the NGC objects were a ghost of their normal selves but the Messier globular clusters resolved into stars at least partially.


Other star clusters I looked at included the open clusters NGC-6709, NGC-6633, the Double Cluster and M-11. However I did sketch three objects in this rich region of the sky for nebulae and star clusters. The first object is the rather small but rich open cluster NGC-7063 in Cygnus. Comprised of around ten brighter stars arranged in a crooked X, with fainter members mixed in, NGC 7063 is actually a fairly nice open cluster for light polluted areas. It stands out well from the surrounding star fields at 149X through my 10-inch Dob. It looked a little more impressive through the 15-inch, but basically the same I suspect due to the fainter stars being affected by light pollution.


Another favorite object I paid a return visit to was the small and very bright planetary nebula NGC-7027. This planetary nebula is very bluish and easy to spot in small telescopes such as my 6-inch F/8 as a small electric blue, oval shaped disk. In larger telescopes at higher magnifications the central star comes into view. Curiously, it is displaced from the apparent center of the nebula and the nebula itself is reminiscent of an oyster shell at 375X through my 10-inch telescope. At 572X through the 15-inch this object took on a bizarre appearance, the clumpiness of the nebula became very apparent and the central star shone brightly. Perhaps NGC-7027 is a bi-polar nebula like many other planetary nebulae, with one lobe pointing towards us and the other obscured by dust expelled previously by the central star while it still was a red giant. No nebula filter was needed to view it well with any of my telescopes from the driveway.


The final object is NGC-7160, a compact but rich open cluster in Cepheus unknown to me until I noted it being plotted on my Sky & Telescope Pocket Sky Atlas.  Many open clusters are drowned out by light pollution at home, but I was pleasantly surprised to find it to be a small open cluster with bright stars that enabled it to stand out from the background sky glow. It responded well to the 6.7mm Explore Scientific 82 degree eyepiece I used which gave a magnification of  196X through my 10-inch F/4.5 Dobsonian.

I've recently acquired four Explore Scientific 82 degree eyepieces with focal lengths of 14, 8.8, 6.7 and 4.7mm. With a huge 82 degree apparent field of view, peering into one is more like looking out of a visor on a space suit's helmet or a window aboard a spacecraft than looking though a telescope. The much larger true field of view makes finding and keeping objects in sight much easier as well. Sharpness, light transmission and color fidelity is excellent, without flare or filed curvature. They work very well in F/5 and below telescopes and are ideal for deep sky objects such as galaxies. If anything, the only drawback to these marvelous eyepieces is the eye relief being too short to be used while wearing eyeglasses. They come pretty close to the performance of Tele Vue Naglers, but at a much lower price. They have full multi-coatings on each surface of every element and are sealed and nitrogen purged to keep contaminants out. For the money they are an excellent buy.

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