Tuesday, December 25, 2018

 

Merry Christmas 2018 from the Astro Blog!



I’m busy with a new book (and maybe a revised edition of an old one), writing for Sky & Telescope with some regularity, and don’t have a lot of time for the old blog right now. However, I couldn’t let Christmas pass without at least a short post.

What’s been going on here astronomy-wise? Clouds, that’s what. But in the days leading up to THE BIG DAY, I did get a few nights good enough to warrant dragging my 10-inch Dobbie, Zelda, into the backyard. Admittedly, she hasn’t been used much in the last year, and I was curious to see what I thought about her three-and-a-half years down the line.

Why did Zelda, a basic solid-tube Zhumell (GSO made) Dobsonian, come to stay with me in 2015 (can it really have been that long)? Mostly to replace my hallowed truss tube reflector, Old Betsy, who was destined to go to a new owner in the winter of that year. Betsy had become too much for me to handle thanks to a back injury I’d sustained. One afternoon, out of curiosity, I booted up her computer, a Sky Commander DSC rig, and the last date in it indicated she hadn’t been used in well over a year and a half.

So, Betsy had to go, but I still wanted a little aperture for the visual deep sky, and set about hunting for something more suited to my new realities (which in addition to my reduced ability to lift heavy telescopes included a fairly decent backyard for routine observing). I had an 8-inch Dob, but that just wasn’t enough for some of my backyard observing. Obviously 12-inches (and up) was too much. That left a 10-inch aperture solid tube Dobsonian.

Why a solid tube? In apertures under 12-inches, I find one to be easier to lug around than a truss tube job. It's a pain to have to disassemble a truss tube's tube. Even if you can leave it in one piece, it's still easier (for me) to manage a solid tube in the process of getting it out into the yard.

Anyhow, after I settled on a 10-inch Dob, a solid tube Dob, the questions became: “What sort of solid tube Dobsonian and from whom?”  The first question was easy to answer. I didn’t think I’d be chasing Herschel 2500, PGC, and UGC galaxies from my back 40. I’d be after the relatively bright stuff. Stuff I could locate with fair ease even in my compromised skies with a 50mm RACI (right angle/correct image) finder and a zero power Rigel Quick Finder site.  No goto or even digital setting circles required.

That left the question of where to buy. Which was a little more difficult. Orion, of course, was (and is) a big player in the solid tube Dobsonian game. They had some nice ones back in 2015; especially their goto/tracking models. As above, though, I didn’t want goto and tracking. Their standard (from Synta) Dobs were a little more expensive than the competition, and didn’t offer the features of the other widely available (at the time) brand, GSO. Since I preferred GSO, that also eliminated the Syntas Synta sells themselves under their SkyWatcher brand.

The GSO Dobs, which are still available (sometimes even from Orion) had some features I really liked. While not everybody agrees, I loved the smooth, easy Lazy Susan bearing on the azimuth axis. The knobs that adjust altitude tension were far better, I thought, than the silly spring tension system the Syntas from SkyWatcher and Orion had.

Another huge factor was the GSO accessory lineup:  an excellent 2-inch two-speed Crayford focuser, a 50mm RACI finder, a pair of eyepieces including a decent 2-inch 30mm wide-field, an eyepiece rack, a cooling fan for the OTA, and a laser collimator.

OK, ya’ll…I’ll fess up. The biggest selling point for your penny-pinching old Uncle Rod? In mid-2015 you could get a 10-inch shipped to you for less than 500 bucks (yes). That was made possible by a big and now gone scope retailer, telescopes.com (Orion now owns that domain name), a subsidiary of the enormous Hayneedle operation. Not only did the 10-inch Zhumell-branded GSO go for a great price, they had it on my front porch in two days.

From the time Zelda arrived, she was a comfortable scope for me. She remains set up in the sun room. When it’s time to observe, I separate OTA from base—the OTA will stand safely on its own vertically—get the mount into the backyard with the aid of a nice carrying handle, return for the OTA, carry it across the deck and down three steps, and I am done. There’s also the fact that I can leave the telescope set up in my secure backyard for days at a time if I get a good, clear stretch. All I have to do to begin observing is remove her Telegizmos cover.

It doesn’t do much good to be able to get a telescope into the backyard in a hurry if it takes a long time to acclimate to outdoor temperatures so it can deliver its best images. The built-in battery-powered cooling fan turned out to be less of a mere gimmick than I thought it would. It really helps get the telescope acclimatized and ready to observe in as short a time as possible. I generally run the fan the entire time I’m observing, and have never noticed any sort of vibration even at high power.

Such were my thoughts on this year’s Christmas Eve as I waited for dark. Zelda had been set up for three days while I used her to test a product for an upcoming Sky & Telescope Test Report. That was done. Tonight, it would be strictly fun observing including my traditional Christmas Eve look at M42. Alas, it would be about an hour before the Great Nebula was well placed for observing. What could I look at till then? How about the little comet that’s caught everybody’s attention, C46/P Wirtanen?

The visitor is currently passing through Auriga, and while the constellation wasn’t very high up—it was just above the roof of the house—I couldn’t wait for it to get much higher. A full Moon would shortly be on the rise, and would no doubt extinguish the comet. A quick look at my fave astronomy/planetarium program, Stellarium, showed me where the sprite lay:  just north of and midway along a line drawn between Capella and Menkalian (Beta Aurigae).

I began hunting around with a 27mm ocular, but kept coming up empty. Hmm. The sky was bright to the east where the Charioteer was hovering. That is, in fact, the most light-polluted area of my sky. How do you deal with a bright sky background? One way is by increasing magnification, spreading out the sky glow. In went my vaunted Happy Hand Grenade, a 16mm 100-degree eyepiece once sold by TMB, Zhumell, and others.

A little slewing and a little staring soon turned up a something. Which eventually morphed, as I concentrated and used averted vision, into a little more than that. There didn’t seem to be a star-like nucleus, but there was a subtle central concentration and brightening. The coma wasn’t round; it was distinctly oval. I almost convinced myself I could see a hint of a tail.

After admiring the comet—such as it was—for a fair amount of time, it was time for target two. What’s one of the best objects for urban and suburban observers other than open clusters? Small and medium-sized planetary nebulae. Riding high was one I hadn’t visited in quite some time, NGC 7662, the Blue Snowball.

At magnitude 8.5 and a size of 37”, the Snowball is just about perfect for a suburban sky watcher. Certainly, it was not a challenge for Zelda. Well, not after I found it, anyway. While NGC 7662 was good and high, in my somewhat hazy skies its area was somewhat star-poor. Nevertheless, after consulting Stellarium, the object was in the field of the Happy Hand Grenade in short order.

At 78x, NGC 7662 looks a lot Jupiter shining through clouds. A large, slightly oval, slightly dim, slightly soft-edged disk. And that is about it—well, other than that, as its name suggests, the nebula is slightly (very slightly on this night) blue-tinged.

Is the above all there is to see of the Blue Snowball? Not quite. Inserting my 4.7mm 82-degree Explore Scientific eyepiece and adding an OIII filter to that brought out subtle hints of detail. It was clear the nebula isn’t just the bright and featureless disk it appears to be at low powers. At high power, it shows subtle darker and brighter patches near its center, hints of the inner ring visible in long exposure images.  

What else did I notice on this night? How good Zelda’s primary mirror is. Say what you will; the Chinese telescope factories have their game down. Their optics are almost universally good and consistent, and have allowed many of us to own telescopes better than we ever thought we would.

Blue Snowball essayed, it was M42 time. I was not to be skunked this Christmas Eve as I had been the last couple of years, but it was a pretty near thing. High clouds were beginning to roll across the sky in advance of a front that will trouble us over the next week or so. For now, however, the sky was holding and I was granted my first good look at the nebula this year.

How was it? The haze was undeniable, but there was still so much to see. Not just the huge “wings” of nebulosity, but the fascinating stars of the Trapezium and the many other tiny and brilliant suns scattered across the cloud. Soon, I wasn’t just seeing the nebula with my eyes, but with my mind.  

I began recalling views of Christmases past stretching all the way back to Christmas vacation 1966 and my first look at this incredible wonder. I haven’t seen the nebula every Christmas Eve. Sometimes clouds have intervened, and sometimes other things have kept my eye from a telescope, but to me it will always be the ornament of ornaments.

Nebula admired, and memories reviewed, it was time to ring down the curtain on this observing run and another Christmas Eve. I covered the scope, and was soon inside, relaxing with the cats and wondering whether I needed to watch It’s a Wonderful Life one more time.

Merry Christmas, everybody! I enjoyed bringing a new blog article to you after a long recess. So much so that I plan on doing more as summer comes in (especially if summer somehow, someway brings clear skies with it!). What else is there to say? Dicken’s still says it best: 

“It was always said of him [Scrooge], that he knew how to keep Christmas well, if any man alive possessed the knowledge. May that be truly said of us, and all of us! And so, as Tiny Tim observed, God bless Us, Every One!"

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