After ogling the Orion Nebula in my new observing site on January 7, I got a little overzealous and made the mistake of returning with my AR 102 just after a rainstorm, on a humid night that soon clouded over. Hunched over in the mud, I could barely make out anything, and I soon enjoyed the company of a big, barking dog. Someone turned on some really bright spotlights at Sidwell Friends School that I can't remember seeing last time, so observing any deep space objects was out of the question. All in all: a disappointment. On a partly cloudy night roughly a week later, I stepped out with my 15x70 binoculars and returned to the park. The lights were on again, but I found a dark shadow under hill that shielded me from the glare. I reclined on the hill and had ethereally beautiful view of the Pleiades and Hyades open clusters, which are now too near zenith to be easy targets for my refractor. Of the two, the Hyades cluster impressed me more, both because I know it's relatively near Earth (just a 150 light year trip!), and because bright, crimson Aldebaran contrasted strikingly with the surrounding stars. Over a week went by before the sky cleared again. Tonight, on February 7, I ventured out with my AR 102 to catch a glimpse of the Moon, Venus, and Mars. It was windier than I expected so the seeing was quite poor, and it again so cold that my hands quickly turned into claws. Nevertheless, the waxing crescent Moon was striking even at 20x. I tried to take a picture using my iPhone and a little gadget I picked up that fastened the phone to my eyepiece. However, the results were disappointing, and I found it hard to keep the phone positioned over the eyepiece. Money poorly spent, it seems. Before long, I wheeled my telescope from the Moon to Venus, which was beginning to approach the western horizon. Venus is nearing inferior conjunction, which means that it's getting close to the Earth. It is, therefore, both extremely bright and fairly big through the eyepiece. I have always found Venus disappointing, since uniformly bright clouds shroud the planet and prevent visual observers from seeing much more than a featureless crescent. This time, I could make out that crescent just fine at 132x, but it bobbed and flickered in the turbulent atmosphere, and chromatic aberration surrounded it with a purple halo. Not the best view. Mars was little better: it's now so far from Earth that it's just about impossible to see any surface features using my little refractor.
Yes, the seeing was poor, but I wondered whether my optics were also a little soft. It seemed hard to focus the telescope. I turned to a really bright star - the white giant Sirius - and decided that the view was, indeed, a little fuzzy. I from my old eyepieces to a brand new, variable magnification eyepiece and suddenly noticed that the view was a bit sharper. Maybe I'll have to clean those older eyepieces. My hands were about to freeze off, so I turned to give the Moon a last look before packing it in. Using the variable magnification eyepiece at 83x, the view was just spectacular. In fleeting moments of good seeing, the mountains on the crater rims suddenly popped out in razor sharp detail. It felt like I was tumbling down towards them from an unimaginable height. With my telescope and eyepiece cooled down, I could make out no chromatic aberration at all. All in all, two satisfying observing nights and one disappointment. Urban observing isn't easy, and with my telescopes it's all but pointless for most deep space objects. Still, it's hard to describe the magic of those stunning views of the Moon, or the standout Winter star clusters.
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I received my Twilight I mount yesterday, and my 4-inch, AR 102 refractor arrived a few days earlier. It snowed in the afternoon, but cleared up around sunset. At the same time, I scouted a new observing site, in the park just east of Sidwell Friends School. Bright lights from the school illuminate part of the park, but it's better than my usual observing site. Despite the bitter cold, I decided to pack my telescope and give it a go.
By the time I arrived at the park, it was only a few minutes to 9:00 PM. Mars and especially Venus were low on the horizon, glittering behind a tangle of trees. I spotted Mars through my finderscope, but I'm not sure if I ever had it in my telescope's field of view. It's awfully far from Earth right now and its apparent size to observers from Earth is tiny (just over 5 arc seconds). I used a 15 mm eyepiece, so the magnification through my telescope (which has a focal length of 663 mm) was only around 44x. Barely enough to make out a disk. The half moon was high in the sky - almost at zenith! - and of course it was a much easier target. I could now fiddle with the finderscope to align it with my telescope. I used a 33 mm eyepiece, so my magnification barely reached 21x. I could comfortably fit the whole moon into my view. It was almost painfully brilliant, but utterly breathtaking. The detail was incredible, and I could scarcely make out any chromatic abberation (an optical distortion common to achromatic refractors). By now, my telescope had cooled down to match the temperature of the air, so the image was crisp. It struck me that the optical quality of the telescope seemed higher than that of any other telescope I've used before. It's not a long list, but still: I was impressed. Orion was high in the sky, too, so I trained my telesope on my real target in tonight's skygazing: the Orion Nebula. At 44x, I could easily make out the Trapezium Cluster: four enormous stars at the heart of the nebula that may be moving around a huge black hole. The stars were glittering pinpoints. I could see obvious nebulosity, too, but there wasn't much detail amid the glare of the moon and the city lights. I screwed an Orion ultrablock narrowband filter into my eyepiece and had another look. The filter only lets in light that shines at the wavelengths of emission nebulae, such as the Orion Nebula. This time, the Trapezium was harder to discern. Yet by using averted vision - by using my peripheral vision, and thereby activating the light-sensitve rods in my eyes - I clearly made out two wings of boiling green gas. It was breathtaking. For a moment, I forgot how cold I was. Lastly, I added a barlow lens (doubling my magnification), screwed in a yellow filter, and turned back to the moon. At 88x, the detail on the lunar surface was spellbinding. I nearly lost myself tracing subtle shadings in the lunar "seas." Yet when the Northwest breeze picked up and the windchill dipped to -15°C, I realized it was time to go. With numb and borderline frostbitten fingers, I packed up my icy telescope. All in all, a great (but frigid) observing session. The AR 102 impressed me, as it has many other amateur astronomers. The telescope cooled quickly and afforded some remarkably crisp views that were a definite step up over my similarly-sized Celestron (which I'll now move to Winnipeg, where I often stay over the summer). The mount, focuser, and diagonal were also all superb. The straight through finderscope is predictably hard to use, however. It looks great, but I'll probably replace it either with a red dot or right angle correct image finder. Still, not a big deal. I also used a nebula filter for the first time, and enjoyed learning about its advantages and limitations. Moreover, I used averted vision more effectively than I ever have before. The yellow filter was a first for me, too. It helped me pick out some fresh details on the moon, but the false color was a little distracting. Perhaps I'll use a dedicated lunar filter next time. And most importantly: I observed a deep space object (DSO) from a big city for the first time. The didn't measure up to what I've seen with a similarly-sized telescope (a 6-inch reflector) in the countryside, but still: I was blown away by what I could make out. One thing I'll definitely need: a foldable camping chair or stool. Kneeling in the snow doesn't cut it. After a hot, clear day that lacked the crushing humidity I've come to associate with DC summers, I decided to take out my new 4-inch, Celestron Omni XLT refractor. Mars was just a few months from its opposition - its closest point to Earth - and it was fairly high in the sky. Saturn was close to the horizon, but still easily visible. I'd say seeing was around a III, and the transparency of the sky was around 2-3, owing to all the light pollution we have down here. I set up my telescope in front a few apartment buildings, on a grassy knoll below an opening in the trees.
I started with Saturn. With a 25 mm eyepiece, my magnification was around 26x. I could clearly make out Saturn's rings and at least three of its moons, but little else. I plugged in a barlow lens and a 7 mm eyepiece. That increased my magnification to 133x. Now, the view was magnificent. Not only did I clearly discern the Cassini Division - a gap in Saturn's rings about as wide as the United States - but I also spotted a mottled grey cloud belt near the planet's equator. It was, by far, the best view of Saturn that I've ever had. Next, I turned to Mars. By late August, the apparent diameter of the planet was around 11 arc seconds: roughly half as big as it gets near its opposition, but well over twice the size it will be in January. Using the same eyepiece, lens, and magnification, I clearly made out the planet's gibbous, waxing disk. As I watched, the atmosphere above me stabilized and a dark surface feature on Mars shimmered into view. It was very indistinct on the little globe, but definitely there. After about half an hour, Washington's resident Asian Tiger mosquitoes found a way through my repellent. I got a few last glimpses of Mars before they hounded me inside. Overall, this was one of the best observing sessions I've ever had. Until now, I'd never (clearly) identified the Cassini Division, or made out dark patches on Mars. I distinctly remember eying Mars with a 12-inch reflector I used to own, and seeing nothing more than a boiling red ball. The optical quality of my little refractor really impressed me. I didn't notice any chromatic abberation, not even on bright Mars. Everything else is a little sketchy, however. The diagonal was a child's toy, so I quickly replaced it with something better. The focuser isn't much better, and I can't afford to update that. The mount is also a bit wobbly. It's light, at least, but it's awkward and therefore surprisingly difficult to carry. Summer observing in Washington can be hard, given the heat and mosquitoes, but I'm glad I stepped out tonight. |
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