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Observing the Way It Was Meant to Be Nothing Is Better Than Observing Under a Dark, Clear, Steady Sky

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Observing the Way It Was Meant to Be Nothing Is Better Than Observing Under a Dark, Clear, Steady Sky THE CIGaR GALAXY (M82) in Ursa deep-sky observing Major is a great object for 6-inch or larger telescopes. Through a 30-inch What we saw through a 30-inch telescope under an inky black sky scope at 736x, however, it ranks as a blew our minds. ⁄ ⁄ ⁄ BY michael e. Bakich spectacular sight. Tony and daphne hallas Observing the way it was meant to be Nothing is better than observing under a dark, clear, steady sky. Wait, one thing’s better — observing that sky through a large scope. In February, I had the opportunity to do just that under the pristine conditions at Arizona Sky Village (ASV), located in Portal, Arizona. As a guest of real-estate developer Eugene more detail you’ll see. If you double the Turner, I had 2 nights with Turner’s superb aperture, you capture 4 times as much 30-inch Starmaster telescope. light. So, an 8-inch telescope gathers 4 The 30-inch is a high-quality Newto- times as much light as a 4-inch. nian reflector on a Dobsonian mount. I’d But there’s another advantage to all the THE GhOsT OF JUPiTeR (NGC 3242) is a used this telescope one year earlier, with light a large scope collects. The object may small object. Its bright inner sphere mea- Astronomy’s editor, David J. Eicher. We appear bright enough to trigger your eyes’ sures only 25" across. Seeing the 40"-wide observed many celestial wonders in Orion color receptors. A planetary nebula that outer halo and fine details requires a large and the rest of the winter sky. One of us looks whitish-gray through a 6-inch tele- telescope and high magnification. would call out an object, and Turner would scope may show shades of aqua or blue ADAM BLOCk/NOAO/AURA/NSF direct the telescope toward it. through a 12-inch instrument. The other factor influenced by increas- scope has a resolution of 1.14" and an 8- The bigger, the better ing aperture is resolution, the ability to see inch scope’s resolution is 0.57". The quality Aperture, the size of a telescope’s main fine detail. In the simplest formula that of Earth’s turbulent atmosphere over a lens or mirror, offers two advantages: defines a telescope’s resolution, called particular site determines a telescope’s light-gathering power and resolution. Dawes’ limit, the resolution (in arcsec- true resolution, but a large scope starts The more light a telescope gathers, the onds) equals 4.56 divided by the tele- with a bigger advantage. brighter the image will appear and the scope’s aperture in inches. So a 4-inch The man with a plan Not wanting to waste a moment of such high-quality observing time, I prepared an observing list of 30 objects. During the 2- night adventure, I observed every one of my targets, plus many more. Because it was February, sky objects naturally divided into two classes. In the early evening, the winter Milky Way with its nebulae and bright star clusters domi- nated the view. After midnight, the region 19th-century observers called the “realm of the nebulae” rose into view. The 30-inch sTaRmasTeR Dobsonian-mounted reflector at Arizona Sky Village takes Astronomers now know these “nebu- advantage of the dark, steady sky there. All observations were through this scope. eugene Turner lae” are galaxies. Traditionally, the three © 2010 Kalmbach Publishing Co. This material may not be reproduced in any form ⁄ ⁄ ⁄ 62 Astronomy July without08 permission from the publisher. www.Astronomy.com THE hORSEHEAD NEBULA (B33) in ReFLECTiOn NEBULA m78 in Orion pres- Orion may pose a challenge to 12-inch Luckily, ASV met both criteria for suc- ents a scalloped appearance through a however, because they ran out of eyepieces and smaller telescopes, but ASV’s 30- cessful galaxy observing: Turner’s scope large telescope. You can’t see its gas in before we reached the sky’s limit. inch Starmaster reflector rendered it offered 30 inches of aperture, and the sky motion, but you can see the result of that At a final magnification of 736x, we immediately visible. r. JAY GABANY is among the darkest in North America. movement. DANIEL VERSCHATSE had to pan across the galaxy. Each subse- quent magnification revealed some new stars of the Spring Triangle asterism — hello, old friends chose open cluster M46 (with embedded detail in this celestial wonder. Arcturus (Alpha [α] Boötis), Spica (Alpha Although I was understandably eager to planetary nebula NGC 2438) and the Night two was filled with more Virginis), and Denebola (Beta [β] Leonis) begin, it wasn’t anticipation that led me Ghost of Jupiter (NGC 3242). terrific objects. For many in the — mark the realm’s boundaries. out during evening twilight — it was prac- The Ghost always has been one of my group, the highlight was reflection Galaxies are the toughest class of celes- ticality. For in the south-southeastern sky Sirius B favorite planetary nebulae. But where I had nebula M78 in Orion. tial objects to observe. Most of them are sat one of amateur astronomy’s all-time seen only a bluish ball with scant detail This bright (magnitude 8.3) faint and large. While planets and plan- observing challenges: Sirius B. before, the view through the 30-inch left object easily allowed us to use 400x etary nebulae occupy only arcseconds of This white-dwarf star shines 10,000 me speechless. At just 184x, a large sphere and above and showed structure I’d sky, galaxies stretch for arcminutes. Gal- times fainter than Sirius and currently lies SIRiUs B currently lies 8" from its much occupied half the field of view. Inside lay never seen through other tele- axies’ sizes give most of them low surface only 8" from its brilliant companion. brighter companion, the largest separation another, brighter sphere, with extensions scopes. The large cloud seemed to brightnesses. To see detail in them, you Observing this pair during twilight cuts in many years. Spotting it requires high like those of a barred spiral galaxy. In the wash over the small features, giving must use at least an 8-inch telescope. Sirius A’s glare. I spotted the B star easily, power, a steady sky, and a high-quality tele- middle, the central star blazed away. the object a three-dimensional appear- Low surface brightness means you must and several in our group (a mix of about a scope. NASA/ESA/h. BOND (sTsci)/M. BARSToW (UNIV. oF LEICESTER) Near the end of the first night, another ance. Amazing! avoid light pollution. For galaxy-watching, dozen ASV residents and visitors) saw it a observer asked if we could take a look at even a large telescope proves useless under couple of hours later when Sirius sat high- ing my best view ever of this “challenge” the Cigar Galaxy (M82) in Ursa Major. aim big an urban sky. And, because galaxies con- est in the southern sky. object: It filled about one-third of the field Turner swung the scope around, and there This two-night, big-scope session ranks as tain all kinds of objects, their light isn’t Next on the list was the often-elusive of view, with the horse’s nose pointing sat the starburst galaxy in all its glory. one of my all-time best observing runs. confined to one spectral zone. So any type Horsehead Nebula (B33). When I asked down. It was so easy to see that, the next After viewing it at 105x, my friends The dark, steady sky above Arizona Sky THE ESKIMO NEBULA in Gemini is small, of filter actually worsens the view. Turner to point the 30-inch toward it, I night, Dave Eicher saw it after coming out- started using eyepieces that gave more and Village, Turner’s hospitality, other excited less than 1' across, so you’ll need high mag- heard a few gasps, and several other people side from an illuminated room — before more magnification. Usually, this activity observers, and the 30-inch scope resulted nification to see its details. One advantage michael e. Bakich is a senior editor of said, “I’ve never seen that.” his eyes had a chance to dark-adapt! stops when the seeing (a measure of the in two nights I’ll never forget. Next time of a large scope is that it collects lots of astronomy who has a severe case of aperture “Tonight’s your lucky night,” I thought, As I checked off other faint wonders, I atmosphere’s steadiness) begins to degrade someone asks you why you want a bigger light, making the magnified image brighter. fever. He'll own a giant telescope one day. smiling. Then, I was at the eyepiece enjoy- felt the need to share a few bright objects. I the image. I guess I forgot where we were, telescope, hand them this article. PETER AND SUZIE ERICKSON/ADAM BLOCk/NOAO/AURA/NSF 64 Astronomy ⁄ ⁄ ⁄ July 08 www.Astronomy.com 65.
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