Tuesday, September 29, 2015

Breaks in the weather

After a very cloudy, murky and rainy summer, even for the sub-tropical Gulf Coast, some breaks in the weather came my way. Two weeks ago I drove out to the darker site the local club uses for its members only stargazes, and found myself alone there. At first it looked like the weather was going to render the trip futile, but the sky conditions improved as the evening wore on. By 10 p.m. skies were as clear as I had seen them for months, and the Milky Way was clearly visible overhead. The Great Rift was apparent. Other deep sky objects such as the Andromeda Galaxy and the Lagoon Nebula were visible to the unaided eye, along with the very evident light pollution from my city and others around it. Nevertheless, the seeing was not unbearably bad for a night where a weather front had just passed by and the transparency was good. After setting up and waiting for darkness to fall, I initialized the digital setting circles began observing. It was a poor night to be looking at the moon and planets, but a good one for galaxies and nebulae.
I had a number of objects in mind for observation and or sketching that I haven't seen before, but most were too faint for the 15-inch under the sky conditions I normally have to work with. So I looked at many familiar object to take in the view and enjoy the first decent night that came along without a bright moon to wash out faint deep sky objects. One such object was the trio of galaxies NGC-7769, 7770, and 7771 in Pegasus. NGC-7769 and 7771 I've easily located with my 10-inch, but the much smaller and dimmer galaxy NGC-7770 went unseen until I turned my 15-inch on the trio. The brightest galaxy of the three is NGC-7769 at magnitude 12.1. It is a Sa or Sa-b spiral galaxy with a nearly round or somewhat elongated shape. NGC-7771 is at magnitude 12.3 with a highly elongated shape and a bright core. Faint little NGC-7770 is round and shines feebly at magnitude 13.6. Under poor skies it's a difficult object to see. 

Of the fifteen globular clusters discovered during a survey at the 48-inch Schmidt telescope at Mt. Palomar Observatory, Palomar 8 is by far the easiest other than Palomar 9 which is also known as NGC-6717. Faint, but fairly large, it has been spotted with small telescopes from dark sites. However from the light polluted area where I observe from, I have only found it with the 15-inch so far. The fact that even along the Gulf Coast, it doesn't get very high in the sky and unfortunately that means I was looking at it through a lot of light pollution, Still at 111X it was quickly located using my lap top and Sky Tools software, which interface with the Sky Commander digital setting circles I use. The globular cluster shows a weak central brightening, and at times it did seem to show hints of a few of its stars. While at the site, I tried my luck on the much fainter and smaller globular clusters Palomar 10 in Sagitta and Palomar 1 in Cepheus. Neither one was visible through my telescope, due to the brightness of the sky.
While at the site, I mostly looked at familiar objects that are soon to be out of sight, such as the Lagoon and Omega Nebulas, the globular clusters M-22, M-28 and M-55. The pair of globular clusters near the tip of the "spout" in Sagittarius, NGC-6522 and 6528 made a fine showing at 111X in the same field of view, as did the globular cluster NGC-6540 and the planetary nebula NGC-6445. I spent some time looking over the Veil and the Crescent Nebula in Cygnus, and spotted the open clusters King 10, 18 and 19 in Cepheus for the first time. The galaxy NGC-6946 and the open cluster NGC-6939 were a striking pair amid the dense star fields along the Milky Way. Soon the annual Deep South Regional Stargaze will be held, and I am preparing to attend this year. With luck, the weather this weekend will be good and I can revisit the summer Milky Way before turning my attention to the numerous fall galaxies in reach of my telescopes.