So I may have contracted a mild case of aperture fever. Not the first time, and likely not the last. I caught a glimpse of the Ring Nebula with my 100mm Takahashi recently, and part of me was impressed. With averted vision I could just make out a ghostly grey smoke ring - not bad, considering the bright urban sky. Yet the view made me wonder what it might look like through something bigger; viewing the moon made me wish for even higher magnifications and just a bit more light. I like my C8, but its optical quality isn't quite on par with that of my fine refractors. And while it cools down in 40 minutes or so if the weather is mild, that won't cut it in the winter. So, I bought a Takahashi Mewlon 180. It turned out that I had a lot more money squirreled away in my university accounts than I expected, and I can only spend it on research or research-related equipment. That meant telescopes, and the Mewlon, I felt, would fulfill all my needs. It squeezes a lot of aperture into a package that's almost as small as a Catadioptric, except it's a Dall-Kirkham reflector, which means it doesn't have a corrector at the front and therefore cools down quite quickly. It's also a Takahashi, and that all but guarantees excellent optical quality and superior craftsmanship. I was tempted to get the (even) pricier 210mm version, but after a lot of reading I decided on something just a bit smaller: something that would cool down even faster and be less sensitive to poor atmospheric seeing. When you take it out of the box(es), the Mewlon does not disappoint. It's the most beautiful telescope I've ever owned. It looks like a jet engine. It's a bit bigger than I expected - of course - but light and wonderfully well-balanced around its slender dovetail. I got a giant and excessively well-added carrying bag for it, which adds significantly to the hassle of lugging it to my observing sites but adds a little peace of mind, too. Within a week of the Mewlon's arrival, the sky was clear and the Moon a beautiful crescent. I carried both the Mewlon and my TV 85 to our observation deck. It was cold, and I used the TeleVue for about 35 minutes while the Mewlon cooled. Once again, the little telescope surprised me. It seems to defy the laws of physics by squeezing so much performance out of such a tiny package. Details on the Moon were simply stunning, and Saturn - despite being low on the horizon, and despite some very mediocre seeing - wasn't bad either. Two things were immediately obvious when I switched to the Mewlon: first, the view was brighter and I could use a lot more magnification, although the Moon was now lower on the horizon and the seeing was worse. Second, my little Berlebach Report tripod and VAMO Traveller mount just couldn't handle the Mewlon like they could the shorter - but slightly wider - C8. The view wobbled, badly. I've already ordered a sturdier tripod (another from Berlebach) and tripod (this time from Stellarvue). Still, I was delighted with the Mewlon. The Moon's terminator was just a bit more detailed, even at relatively low magnifications, than it had been through the TV 85. The view wasn't completely different at those magnifications - a testament to the much smaller TV 85 - but there was definitely more there, and it was crisper than it had been through the C8. At high magnifications - magnifications the TV 85 couldn't match - a new world started to emerge. I don't think the Mewlon had fully cooled down, however, despite the wait, and I wish I could have stayed out just a bit longer. Whenever the Moon is up, I try to take pictures using my iPhone 8. That's as close to astrophotography as I hope to get, at least for now. Although iPhone pictures inevitably have far less clarity, vibrance, and sharpness than views through the eyepiece, I am learning how to take better shots. I've given up on the gadgets that some telescope makers sell to mount the phone in front of the eyepiece; in my experience, the results are too often disappointing. Instead, I've learned to hold my hands more steadily - steadily enough to focus the phone on the object I'm observing. I've also learned to enhance the clarity and definition of the photos I take, and then slightly increase the settings for shadows, vibrance, and occasionally black point to better approximate what I'm seeing. My most important lesson, however, is to take videos of anything other than zoomed out views of the Moon. By taking videos, I can freeze on frames in which atmospheric seeing suddenly stabilizes. When I take a screenshot of those frames, the resulting picture is often much sharper than I get by just starting on picture mode. Some objects that are totally washed out otherwise - like Saturn - start to look like themselves when I take a video. I enjoy taking even the decidedly amateurish photos I can get with my iPhone. But at some point, I'd like to try my hand at sketching, like the nineteenth-century observers I've been reading and writing about lately. I doubt my results will equal theirs at first, but it will be fun to try.
1 Comment
At the moment, Lyra and Hercules are high in the high, and Uranus and Neptune are near the annual oppositions. This got me thinking. My refractors are everything I'd hoped they'd be, but would they really have enough aperture to satisfy me if I wanted to glimpse the ring nebula? What would they show me if I wanted to track down M13, the Hercules Globular Cluster - which to my continual amazement I'd never seen (until this entry)? Would they show me any color if I managed to find Uranus, or would the planet be just another grey dot? I was thinking about these questions and fighting off aperture fever - a menace that has claimed me before - when I received news that the research budget I receive from my university would be doubled, as of this year. One way I use my telescopes is to imagine what astronomers from a bygone age might have seen when they looked at the Moon and Mars, which in turn helps me to write about the history of space. That's research, so it's easy for me to justify astro-expenses from my research account. And then - the final nail in the coffin - I spotted one of Celestron's six-inch schmidt cassegrain telescopes (a C6) on sale, brand new, for less than $400. I bit the bullet and bought the telescope, in the hopes that I might at the very least be able to use it with my students (with whom I'd rather not use much more expensive telescopes). At first glance, the C6 certainly looked nice with my sturdy little mount and tripod (a Berlebach Report 312 tripod and VAMO Traveller mount). Yet on closer inspection, it had no fewer than three little blemishes - including a spot on the corrector - and that was just too much for me. I returned it, disappointed . . . and then noticed an equally good sale on an eight-inch, orange-tube, Nexstar SCT. The C6 had seemed rock solid on my mount and tripod, so I suspected that the C8 would be sufficiently solid, too. The C8 was also lighter than the Edge HD that I had recently given away. With a sale so good, I couldn't resist pulling the trigger. The finish on these Nexstar tubes - like that on the Edge tubes - is just much nicer than the glossy black on other Celestron SCTs. There's a depth to them and they don't get covered with hand prints as easily. On the other hand, the orange tubes don't have a handle on the back, and that handle is the kind of little luxury that makes everything from stowing to using a telescope that much easier. The wonderful thing about my new mount and tripod is that they're light enough for me to bring both my C8 and my TV 85 to an observing site - like our observation deck, for example. That's a game changer for me, because it means I can observe with a wonderful instrument as the SCT acclimates. I did just that on my first night with my new C8. The temperature was only a few degrees cooler than it had been in my apartment, so after about 30 minutes I hoped that the C8 would be ready to use. I had just been viewing Saturn with my TV 85. The view was crisp and the color was perfect, but the planet bobbed around in the currents coming off my building. I was apprehensive when I switched to the SCT and inserted a 25mm Plossl. Yet to my astonishment, the view was much, much clearer than it had been through my Edge. The planet was far brighter - no surprise there - and a few new moons snapped into view. When I turned to higher magnifications the view abruptly degraded. In fact, in the heat currents coming off our building the TV 85 handled higher magnifications better than the SCT. Still, the crystal-clear view at lower magnifications suggested to me that I had a much better sample than the Edge I'd previously owned. I used the same setup on another night, switching from the TV 85 to the C8 after a half hour or so. This time, temperatures were around 16 degrees Celsius - a good deal cooler than inside. Yet again, the SCT had acclimated completely. I suspect it acclimates more quickly than the Edge, despite the vents on the Edge.
The C8 is about as solid on my mount and tripod as the Takahashi, which is to say a bit less solid than the TV 85, but more than good enough for my purposes. Again, Saturn bounced around. But the rising Moon was spectacular, with extraordinary detail through the TV 85 and - again to my surprise - especially the C8. Once again the C8 did not take high magnifications quite as consistently well as the TV 85, but at times I could glimpse some impressive detail when the seeing cleared up. Towards the end of my short observing session, I decided to hunt for the Hercules Globular, in the hopes of seeing it for the first time. I began with a 55mm, 2-inch Plossl on my TV 85. Although I had to crane my head in some awkward angles, at last - at last! - I spotted the cluster. It was pretty bright on the deck and so the view was dim, but there: I'd found it. Switching to the C8 and using averted vision gave me a very satisfying view: countless tiny stars coming into focus around the core. Someday, I'd love to see it under darker skies. So yes, I remain a refractor guy - the TV 85 is still my favorite telescope - but it sure is nice to have the mobile aperture of a quality C8. I'd always loved the promise of the Edge, and now I have much of it back. I likely won't use the C8 much in the winter, but it will be great to use it with the TV 85 in the warmer seasons. It's been a while since I wrote. I've come to realize that, with young kids, I just about never have the time to do something as decadent as write for fun. And I certainly don't have time to write long articles purely for myself - or the occasional wayward visitor. Yet here I am, writing again while rocking my infant son to sleep. Over the past few years, I've gone through my share of equipment and seen so many beautiful sights. I've learned a lot about what equipment works for me in Washington, DC, and what I most enjoy seeing. Here's a little list: 1. Aperture is absolutely, most definitely, positively not king, and don't be fooled by anyone who tells you it is. Aperture is one very important factor to keep in mind when selecting optical instruments, but by no means the most important. I received tenure this year (!!!), and shortly after I did I had what appeared at the time to be a great opportunity to visit the southern hemisphere. That fell through - I couldn't get a Yellow Fever vaccination on time - but not before I'd used some funds to buy what seemed to me to be the perfect travel telescope: a TeleVue 85. I remember seeing advertisements for TeleVue refractors as a kid, and wondering why anyone would spend so much money on a telescope so small. I went ahead and bought a VAMO traveler - a wonderful little mount - and a carbon fiber photography tripod. Together, the whole setup weighs about 14 pounds. When everything was ready, I walked outside onto the observation deck of my building to catch a glimpse of Jupiter just after its opposition. High, hazy clouds rolled in just as I stepped outside, partly obscuring Jupiter. Yet I set up my telescope - in just a couple minutes! - and had a look anyway. It was hard to make out many details, and I packed it in before too long. A few days after, I walked out on a truly clear night. This time, my first stop was the half moon. I was absolutely floored. I'd never seen the Moon with such astonishing clarity and contrast. I'd thought my Skywatcher 100ED gave me great lunar views; clearly, I was missing out all along. Turning to Jupiter gave me a hint of detail that I'd never seen before. Saturn, despite being very low on the horizon, was a beautiful sight near its opposition. Lately, I've written an awful lot about nineteenth-century astronomers - amateur and professional. Back then, many debated whether small or big telescopes offered the best planetary views. I'd assumed that the debate had been sparked by tensions between amateur and professional astronomers (the amateurs typically couldn't afford the gear that professionals used, with some big exceptions), rather than real experience. Now, I realized I'd been wrong. It occurred to me: if this little telescope gave me the best planetary and lunar views I'd ever had, why did I have so many bigger scopes? It didn't help that the little instrumented exuded quality like nothing I'd ever owned. Everything about it made it an absolute joy to use. The following night I lugged out my 8" Edge SCT, on its heavy mount and tripod. This time, the whole setup weighed in at about 33 pounds. Seeing was better than it had been the night before. I had to know: with an aperture of 200 mm, would it show me even better views than the 85 mm refractor? No. The views were brighter, for sure, but they lacked the crisp contrast that the refractor provided. I saw a good deal less detail on Jupiter, and the Moon wasn't nearly as detailed. I was actually a little embarrassed when two neighbors asked to look through the telescope, because I remembered the glorious views from the previous night. I felt a pang of regret that I hadn't brought the TV 85 instead. That brings me to the second, related lesson: 2. Cooldown, weight, ease of use, contrast (versus brightness), fit and finish, and perhaps above all the local environment (on the ground and in the air): all can be as important as aperture. One reason that views through the Edge quite literally paled in comparison to those through the TeleVue is that the Edge hadn't yet acclimated. Not surprisingly, the Edge can take over an hour to reach thermal equilibrium. These days, with a newborn and a three-year-old, an hour is usually all I have to observe. Moreover, even on a simple alt-azimuth setup, it takes a good 10 to 15 minutes to set up - compared to fewer than 5 with the refractor. It turns out, all of that matters a great deal to me. So does weight. The easiest way for me to use a telescope is to lug it up several flights of stairs. Observing on the observation deck of my building, I've found, can attract a lot of unwanted attention. I like outreach, but observing for me is most enjoyable when it's just me and the sky. Maybe my kids will make me reconsider that feeling, when they're old enough. Anyway, my "best" regular observing sites - they're still far from ideal - are a 15-minute walk away. It's just not haul 40 pounds of gear for that long - especially when you aren't sure that your telescope will acclimate before you have to pack up. That's the other thing: I hate collimating. Yes, I've become pretty good at it, and yes, an SCT doesn't need to be collimated much. But give me a telescope I can set up and look through, right away, with no fuss. Especially when I don't have much time to observe! Then there's our local environment. In the winter, it gets pretty cold here: all the more reason to have a telescope that cools down fast. In the summer, there are mosquitoes: all the more reason to observe fast. The air can be turbulent (though we do have stretches of good seeing): not a big deal when using smaller apertures, but incredibly frustrating with bigger telescopes. In the city, I tend to restrict my viewing to planetary, lunar, double stars, and the really big showcase deep space objects (Orion, for example). In light-polluted skies, I put a premium on pinpoint stars and stark contrast. I've found that high contrast optics can give better views of deep space objects even when those views are dimmer. Lastly, there is just something about a premium instrument that makes you want to use it. Every little thing becomes a pleasure, from unscrewing the dust cap to adjusting the focuser. Yes, it's silly, and yes, maybe it's what you notice when you read too many telescope reviews. But it matters, especially when you're in a hurry. So, my third lesson: 3. I'm a refractor guy, through and through. It's worth noting how personal this lesson is: completely attuned to what I value, where I live, and my life circumstances. That it's taken years and more money than I care to admit to reach that lesson does make me resent the ubiquitous comments on astronomy websites that tell people what telescope to buy. No, the best answer is not always the biggest you can afford. After taking out the Edge that final time, I went on the kind of binge that I still can't believe I had the energy for. I sold just about every piece of astronomy gear I had, including four telescopes, three mounts, and two tripods. I have to say: it often hurt. Away went the telescope - the C8 - that I'd always fantasized about having. Away, too, went a really nice 100 mm refractor: my Skywatcher 100ED. If it couldn't offer better views than my much smaller and more portable TeleVue, it had to go. But I didn't want to sell for the purpose of selling - nor did I feel comfortable with just one telescope. Once I'd ditched just about everything, I agonized over what second telescope I'd like to have. It had to be relatively small, while offering something that the TeleVue didn't - or at least, giving a little something extra that the TeleVue couldn't. I wanted something that I might use when the seeing was really steady, even if it was a bit harder to use. Ultimately, it came down to two choices: a Skywatcher 120ED and a Takahashi FC-100DC. Both are refractors, of course. The Skywatcher is a good deal bigger and slightly less expensive. The Takahashi technically gathers less light, but the optical quality is such that it might actually offer better views of just about everything - especially planets. I eventually settled on the Takahashi. Other 100 mm Takahashi variants have longer focal lengths, which makes them better attuned for planetary observing. Yet the difference is negligible, and the shorter focal length of the DC makes it a more versatile telescope for deep space observing. It also makes it much easier to mount: I could easily use the same mount I purchased for the TeleVue 85. So, to my astonishment, I made a purchase I never expected to make: I bought a Takahashi, one of the most celebrated telescopes in the hobby. My dream is to use the Takahashi for planetary, lunar, and double star observing, especially when I have a bit of extra time, or when the weather is nice enough for a walk to a nearby park. If I have time - hah! - I'll write an update on how it works for me. For now, I'll collect all the little accessories - from a diagonal to tube rings - that Takahashi chooses to sell separately.
It's been quite a journey, but I hope I now have telescopes to last a lifetime. At least, until the next big purchase comes calling . . . . About a year ago, I picked up a Skywatcher 100ED: a "slow" (F/9) 100mm refractor. I haven't written much this year, but wow: suffice it to say, I rarely use any other telescope (and when I do, I come away disappointed). The refractor cools down quickly, throws up wonderful views, and most importantly: never gives less than optimal performance. The only drawback is the length of the tube, which makes it harder to transport and heavier to mount. This past spring, I was lucky enough to design and teach a dream course: "Mars and the Moon in science, science fiction, and society." I asked my students to join me one night to look at the moon through three telescopes: my 100ED, my older AR 102, and a colleague's beautiful, homemade reflector. Students were to find a feature on the Moon and then write about its history: not only how it was created by natural forces, but how it's been perceived, explored, and imagined by people. The night was a smash hit: lots of amazed expressions, and later, plenty of great essays. Of the three telescopes, the AR 102 was clearly a notch below - and its focuser gave us plenty of problems. This summer, Mars reached a very favorable opposition, not long after I wrote about it for the book I'm working on. When I lugged out my C8 to have a look - at around 4 AM! - it instantly (and I mean instantly) fogged over. There is nothing worse than waking up early, walking with 40 pounds for 15 minutes . . . and then having to turn right back immediately after setting up your telescope. From then on, it was all refractor, all the time. Using the 100ED, Mars typically looked like an angry orange ball, shimmering and sometimes boiling near the horizon. Yet now and then I caught fleeting and often uncertain glimpses of what I supposed to be the planet's famed dark streaks and splashes, including - I thought - Syrtis Major. I might even have made out a polar ice cap. My goal for the summer had been to see these sights with no ambiguity at all, so I came away a little disappointed. Mars is hard when it's so near the horizon. Maybe the view will be clearer in 2020 . . . and maybe I'll have even better gear then. One thing is certain: the 100ED is a wonderful lunar telescope. Things never looked so sharp through the C8, nor did the hues include such subtle gradations of grey. I've also never seen Saturn look as good as it did through the 100ED. The Cassini Division neatly divided the rings, and the color was a wonderful, very pale shade of yellow. Glorious. After one night of rooftop observing, I saw something I didn't expect: a brilliant green meteor - or meteorite? - flaming through the sky. Given that we live in Washington, DC - and given the present state of geopolitics - I was momentarily alarmed. But what a sight! Come winter, I wanted to try my hand at something that never really interested me before: multiple star systems. The prospect of seeing a couple stars next to each other never really did it for me, but then few deep space objects are easier to observe from the city. My primary target was Gamma Andromedae, also known as Almach, an apparent double (we now know it's a triple) star system with wonderfully contrasting colors. With Almach riding high in the sky, I had a look one frigid evening. Immediately, I got it: there was something about seeing two incredibly different stars next to each other that's just so beautiful, especially through a refractor. And it sparks the imagination to think about the view from an orbiting planet. Lately, my two-year-old daughter has become ever more interested in astronomy. She loves looking at planets and galaxies in the books I have lying around, she's learned the phases of the Moon, and she's decided on a favorite planet: Jupiter. She's even insisted on having a picture of Jupiter on her bedroom wall! Maybe, in a year or two, we'll have a chance to look through a telescope together. From the time I was a young kid growing up under the dark skies of rural Canada, I dreamed of owning an eight-inch Schmidt-Cassegrain telescope. Glossy advertisements in astronomy magazines promised me that a “C8” would give me the aperture I would need to peer deeply into the cosmos, the portability that would encourage me to peer often, and the robotic gizmos that would unfailingly point me in the right direction. It was an irresistible combination . . . except for the (fittingly) astronomical price. Someday, somehow, I thought, I’d get a good job and save up enough to buy one.
That day arrived late last year, when I found a C8 optical tube assembly (OTA) on sale for a price that seemed hard to beat. And not just any OTA: this was an Edge HD, quite possibly the best mass-produced Schmidt-Cassegrain on the market today. I snapped up the telescope – with a little help from my employer – and waited until I could use it. I waited long, because in cold weather, Schmidt-Cassegrains can take a long time to reach "thermal equilibrium:" the same temperature as the air around them. Until they do, air currents inside their tubes disrupt the view. In the winter, you have to leave your Schmidt-Cassegrain outside for quite a while before using it, and since I currently observe in urban parks that just isn’t possible for me. So I waited for warmer temperatures. Fortunately, they come early in Washington, DC. Tonight, with temperatures in the upper teens, I stepped out with my Edge HD for the first time. Aside from the temperature, conditions were far from ideal. The wind gusted from the southwest, so the “seeing” was far from perfect, and the transparency of the atmosphere also left something to be desired. Wisps of cloud drifted by from time to time, the first signs of a storm system that should be with us tomorrow morning. Yet it was a comfortable night overall, and I looked forward to observing with no risk of frost bite. I set up in my usual observing spot: out behind a police station, in a community garden. Bright street lights are far too close, so I can never develop proper night vision. Yet since I observe in the heart of a little vegetable labyrinth, I'm usually shielded from prying eyes and barking dogs. I have two mount/tripod assemblies that I can use with my C8: the Twilight I setup that I use with my lighter AR 102, and a Nexstar SE computerized mount that came with my (now dearly departed) C6. Both can theoretically handle weights up to around 18 pounds, but in practice neither can quite accommodate the 14-pound Edge HD, with its finder and eyepieces. Still, both are light and small enough for me to walk them the five or so minutes it takes for me to reach my observing sites. This time, I decided to roll out the Twilight I. I wanted to see what I could see with my OTA, and I just didn’t have the patience to deal with occasionally finicky electronics. To minimize the wobbling that usually plagues big telescopes on flimsy mounts, I placed my tripod on Celestron vibration pads. To my surprise, it actually worked fairly well. The telescope shuddered when I moved it and especially when I focused it, but that shudder was not as bad as I’d feared. After unpacking my telescope, I waited around 10 minutes before I lost patience and decided to observe, thermal equilibrium be damned. I snapped in a cheap, 30 mm Plössl eyepiece and wheeled my telescope over to the Orion nebula. The first think I saw when I looked through the telescope was a satellite streaking by. An auspicious start! When it left my view, the Orion Nebula emerged from the inky background. As you might expect, the difference between the Edge HD and my AR 102 was immediately striking. Where the little refractor shows a little arc of misty grey-green light, the bigger Schmidt-Cassegrain reveals delicate tendrils of nebulosity in a giant crescent around the Trapezium Cluster. Next, I reached for in a new purchase. I recently sold my Celestron refractor and used the money to buy a new diagonal and my first quality eyepiece: a 14 mm Explore Scientific 82°. After plugging in the eyepiece and thereby boosting my magnification, I turned to Venus. I was astonished. The AR 102 shows a small, flickering crescent blurred and distorted by chromatic aberration. At 145x, the Edge HD, by contrast, gave a razor-sharp view, even before it reached thermal equilibrium. Since Venus is nearing its closest approach to Earth, when it will be between the Sun and our planet, its crescent is even narrower now than when I last observed it. That made the effect of my sharp, Edge HD optics even more pronounced. There’s no sign of false color with the Schmidt-Cassegrain, so I could fully enjoy the pale, yellow-white atmosphere of Venus. I used a barlow lens to double my magnification to a whopping 290x – the highest I’ve ever used – and somehow the atmosphere (largely) obliged. The crescent flickered in the turbulence but overall remained razor sharp. Although it now filled much of my view, it lost little of its brightness. The view was now truly breathtaking. The atmosphere of Venus looks largely featureless, yet there was an almost magical quality to the zoomed-in crescent. It was amazing to think that this is a world roughly the same size as our own, but with an atmosphere so thick, and so choked with greenhouse gases, that a car would crumple and then melt on the surface. A hell-world deceiving me with the beauty of that delicate crescent. Mars is near Venus right now in the night sky, but it is actually much farther from Earth. As a result, it is roughly 200 times dimmer than Venus, and less than a tenth of the bigger planet’s apparent size. When I trained the Edge on Mars, I was not surprised to find a tiny, featureless globe. The wind picked up, and as it did the seeing worsened. The little red planet seemed to bob and weave across my view. I marveled at how small the disk looked, even at nearly 300x. Space is big. I kept my magnification high and turned to Rigel, a blue supergiant star some 863 light years from us that shines with the almost unimaginable brightness of some 200,000 (!) Suns. Several million years from now, it will explode in a brilliant supernova and its core will become a black hole. Rigel is actually at the heart of a solar system that contains several smaller stars. At 290x, I spotted one of its companions for the first time: Rigel B, actually another star system that orbits the bigger Rigel – Rigel A – at a distance equivalent to 2,200 times the distance between Earth and the Sun. Rigel B consists of two stars between three and four times the mass of the Sun, and one of these might actually be yet another star system consisting of two stars. It’s hard to imagine looking up from the surface of a planet orbiting Rigel Bb, with so many bright blue suns in the sky. Anyway, the Rigel B system is hard to spot with a telescope of six inches or less, so I was happy to glimpse it this time. I finished by taking another look at the Orion Nebula. I kept my magnification at 290x and screwed in my narrowband filter that, you'll remember, only lets in light that shines at the wavelengths of emission nebulae. Now the view was just overwhelming. My eyes were not fully night adapted, and yet: the detail in the nebula around the zoomed-in Trapezium Cluster was just incredible. Boiling grey-green mist. A few closing thoughts. First: this telescope hugely outperforms my AR 102. I expected as much, of course, and the comparison really isn’t fair given the very different roles (and costs!) of both telescopes. Yet I was surprised not so much by how much brighter objects appear through the Edge, but how much sharper they look. Second, the Twilight I mount can hold my C8 in a pinch. The view did wobble at high magnifications, especially during gusts of wind, but this is not a bad grab-and-go setup. It’s pretty amazing that such a powerful telescope can be so portable. Third: I’m beginning to grasp the appeal of “splitting” or “resolving” binary star systems. That’s good, because binaries are some of the few deep space objects that are easy to observe from urban locations. Finally: it sure feels great to have a really high quality eight-inch Schmidt-Cassegrain. I think I’ll keep it. 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. |
Archives
March 2024
Categories
All
|