Saturday, February 9, 2013

Finally, a clear night

The weather for the past two months was one storm after another with clouds, fog and wind in between. Finally last Thursday some clear skies arrived without atrocious weather or a bright moon to drown out the galaxies and nebulae that get through the sky glow in my city. The next few nights after that were an opportunity too good to pass up, so I rolled the 15-inch out to look at both familiar, favorite objects and objects I have never looked at before both at home and from the airstrip.
IC-179 is a small elliptical galaxy that lurks in the fringes of the large, scattered and bright open cluster NGC-752 in Andromeda. Quite faint, it showed itself as a small oval shaped glow with a brighter center. It was surprisingly easy to spot despite the deteriorating skies once I pointed the telescope at the location where the Sky Commanders indicated the galaxy was. The foreground star cluster is by far the more interesting of the two, it's a fine sight in small telescopes that can give a wide field of view.
Unlike the galaxy IC-179, the planetary nebula J-320 in Orion was much harder to spot due to poor seeing and the small apparent size. The night before I went to the airstrip, the seeing finally stabilized enough so I could distinguish it from surrounding field start. At 227X it was a small, clearly oblong disk that had extensions aligned with the long axis of the nebula. In the center, the central star was visible. While it was visible from home without a nebula filter, an O-III and narrow band did make it easier to see. Without a filter in place, it had a greenish or greenish blue tint.
M-33 or the Triangulum galaxy is far and away the most well known object in the constellation Triangulum. However, there are numerous other  background galaxies also visible to amateur telescopes too. One of the lesser examples of Triangulum's galaxies, NGC-890 revealed itself easily to the 15-inch from the airstrip as a somewhat oval object with a brighter center. Like IC-179, it has relatively high surface brightness and was visible through the light pollution that affects the views from the airstrip. This elliptical galaxy revealed little of its structure other than brightening towards the center.

Also in Triangulum lies the small and rather dim galaxy NGC-949. Like NGC-890 it is an elliptical galaxy that has little internal structure except for brightening towards the center. It was somewhat larger, more elongated and had a weaker central brightening than NGC-890. Not one of the finer galaxies of the fall sky, NGC-949 was a relatively easy object for the 15-inch at the airstrip.
Moving on to Orion, I located the reflection nebula NGC-2023 which lies very near the famous but very difficult to see visually Horse Head nebula. Unlike emission and planetary nebula which glow because of excitation by ultraviolet light from nearby massive, hot stars, reflection nebula merely reflect light from stars near or inside them. NGC-2023 is a quite hard object to observe due to the brilliance of the star embedded in it and faintness of the nebulosity. It was fairly apparent at 181X and showed an elongated, irregular outline. Within it subtle patchiness and brightness variations were visible. Overall, it resembled a streetlight in a fog bank.
In the constellation Monoceros are numerous open clusters that are visible in amateur telescopes. NGC-2251 is large, bright and fairly scattered with the member stars varying in brightness. It stands out quite well in front of the background star fields at 142X. The drawing here is centered on the cluster itself due to the very large numbers of stars that are not members also in the field of view. It's quite easy to see from at home despite the light pollution in my city.
Nearby is the open cluster NGC-2252, which resembles a stick figure of a person. Smaller, fainter and a little harder to make out in front of the background star clouds than NGC-2251, NGC-2252 is still a nice sight at 142X through the 15-inch from my driveway. There is a prominent rhombus of brighter stars on one side of the star cluster, and the whole cluster is set amid a very rich star field. Monoceros is a very rich hunting ground for open clusters, as well as nebulae. Owners of small and large telescopes alike will find many treasures hidden among the stars of Monoceros the Unicorn.

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