Sunday, May 10, 2015

 

The Old Fashioned Way


Another Free Comic Book Day has come and gone. Avengers: Age of Ultron is dominating Cineplex screens to no one’s surprise and will likely continue to do so for some time. Flash and Arrow and Gotham and Agents of Shield are winding down for the season. But what’s going on around here? If you read this blog regularly and closely, and especially if you are good at reading between the lines, you are aware I've been going through some changes with a capital “C” (I do not mean by that that I have cancer; I am physically in better shape now than I have been in years) the last several months. I won’t bore you with the details. I will just say they are significant and have affected many things including the way I practice astronomy.

Where have I been in (amateur) astronomy the last 5 – 7 years? I’ve been almost exclusively in the imaging camp. The closest I've come to visual astronomy, usually, has been observing with a deep sky video camera, with one of my Mallincams. Even out in my backyard, my normal setup has included a telescope on a computerized goto mount, a camera, a laptop computer, often a monitor and a digital video recorder, and assorted and numerous cables and power supplies. Lotta stuff. But I was having fun, and my sensitive cameras allowed me to get through The Herschel Project’s 2500 or so deep sky objects more quickly than I’d dreamed I could.

I’ve done some crazy stuff with my Mallincams and DSLRs, from observing quasars out on the edge of creation last February down in Chiefland, to getting the best comet photos (of Lovejoy) of my life. I was used to setting up all the astro-stuff and observing with a monitor or computer instead of my eyes, and didn't mind it a bit. Until I did.

During the Chiefland trip, it became clear my observing habits were, like other things in my life, going to change. Like some other things, they needed to change. In fact, they had to change if I were to continue to observe. This might have happened anyway. I've always swung back and forth between visual looking and more technologically complicated modes of amateur astronomy, and I had been on a big-time imaging jag at least since 2010. But there is no doubt the changes I was going through accelerated my return to eyepieces.

So, I found myself ready—nay, anxious—to go back to a simpler sort of amateur astronomy. Which I differentiate from my “casual” observing. Even at the height of my DSLR and CCD and video observing, I've used grab and go scopes like the two we talked about last week for quick peeps at the sky. When I've wanted to do serious work, however, I've dragged out the C11 and a camera, even just for observing from the back forty. It is that that will change.

I wanted to go simpler. No cameras. No computers (no computerized goto mounts, at least). How would I get there? For me, “simplicity” is spelled d-o-b-s-o-n-i-a-n. In its original and pure form, what you've got with a Dob is a Newtonian reflector on a simple alt-azimuth mount. It’s point and shoot astronomy. Want to look at something? You find it with a finder-scope, a zero-power reticle sight, or setting circles (yes, on a Dobsonian). The scope moves up and down and right and left in, if it has been built correctly, a buttery smooth fashion. There are no motors or even locks for the altitude and azimuth axes. You push the scope, it moves. You stop pushing, it stops. Yes, there are goto Dobsonians today, but not for me.

I’d once embraced Dobs wholeheartedly, if for a relatively short time, at the end of the 1980s and the beginning of the 1990s. Despite having been away from the scopes for many a year, I still have a couple in my inventory with a little more horsepower than the 4-inch StarBlast. The one with the most of that is my 12.5-inch truss tube scope, Old Betsy. She’s always been a stellar performer, and despite not always using her as much as I should, I've never stopped loving the views she’s given me over two plus decades.

I will no doubt be using Bets a lot more now, but she didn't seem to be the telescope for most of the backyard expeditions I had in mind, and maybe not even for many trips to the club dark site. While she’s been modified recently so that she’s a little lighter, she is still not a lightweight. Sure, I could gin up a set of wheels or a wheely-bar system for her, but, even then, getting her into the backyard sounded like work. More work that I want to devote to telescope setup at this time.

That meant my other Dobsonian would be on deck—for a while, anyway. This telescope really doesn't have a name. Or at least a name that describes her in her present (elegant) form. I still call her Old Yeller. That’s because she was originally a Konus f/5 GEM Newtonian (made by Synta) who came to me with a hideous yellow-orange tube.

The Konus worked well despite that garish tube, and certainly paid her way, since I did many of the observations for my book, The Urban Astronomer’s Guide with her. In the end, however, on her non-goto CG5 mount she was just too inconvenient to set up regularly once the book was done. That wasn't the end for the scope, however; my friend Pat needed a non-goto CG5 mount, so we worked out a deal. Pat rebuilt the scope into an elegant neo-Dob, and I sent the CG5 to live with him.

Despite the Dob’s humble ancestry, her f/5 primary mirror is quite good indeed, giving excellent views of the planets. The Konus delivered some surprisingly good images of Mars when it was riding high in 2003, the year of the great opposition. 2003 was about the time most of us had to at least begin to admit the Chinese were beginning to produce some darn good optics.

Yeller in her current form is uber portable; I can easily carry her rockerbox in one hand and tube in the other. She is at least as quick to set up as the C102 refractor, and, naturally, an 8-inch brings a more to the table than the 4-inch. As I said last time, small telescopes have their uses, but if you really want to see lots of Stuff, deep sky or Solar System, from city or country skies, 8-inches is where you begin. The difference between images in Old Yeller and in the StarBlast or the C102 is simply “light years.”

Nothing is perfect, of course, and there is a fault with the scope that needs correcting. Back when Pat and I were buying parts for the pair of 8-inch Dobs (Pat did an identical twin for himself), focusers were not as inexpensive and good as they are now. While we’d both used and liked JMI’s NGF DX3, their lowest priced true Crayford at the time, we didn’t want to spend that much for focusers for these scopes. Since the DX3 had been such a success, we figured the company’s new bargain focuser, the RCF (“reverse Crayford focuser”), would be good too.

I bow to no one in my respect for Jim’s Mobile Industries. I own many of their products and just love ‘em. Except for that misbegotten RCF. It is, I’m sorry to say, just this side of junk. While well built, more or less, the focus mechanism just doesn't work right. It is always too loose at one end of its travel and too tight at the other. You can adjust it so it is workable, but it will never be nearly as good as the cheapest of today’s Chinese Crayfords. Now that I am back to the Dobs, I hope to replace it with a Moonlite, but I can deal with it as is until I can do that.

Alrighty then. With a clear and dry night just before the First Quarter Moon upon me, it was time to get set up. In the interests of keeping it SIMPLE, I left my big observing table, the computer shelter, and all the other gimmicks I’ve used over the last decade in my Shop. What went on the field in addition to the telescope was a couple of wooden TV tray tables and my observing chair.

If you are going to use a low-slung Dobsonian like my f/5 comfortably, you have two choices. You can elevate it by putting the rocker base on some kind of support like the one Orion sells (for way more money than they should if you ask me). That will work if you want to stand while observing, but who wants to stand up to observe if you don’t have to? There is no doubt you will see more if you are comfortable, and the way to be comfortable while looking through a telescope is to sit.

A variety of observing chairs can work with low telescopes. Heck you might be able to get a drummer’s throne low enough to serve. The best solution, though, is one of the sliding seat chairs like my Buy Astro Stuff one. This chair, sold by various merchants as a “utility” chair, will easily go low enough to make me comfortable at the eyepiece of the 8-inch when I am scoping out objects low down on the horizon. The seat has enough adjustment range, however, so I can also use it with my 12-inch. I can access the finder while seated, and only have to get up and rearrange the chair when I move to a distinctly different part of the sky.

Ah, the finder. What sort of a finder would I be using for my initial foray back into old-timey observing? I A Rigel Quick Finder, the Telrad’s cousin. The QF features a Telrad-like bullseye that’s projected onto a beam-splitter glass. That makes the red LED illuminated reticle seem to float before the stars. There’s no magnification, nothing is inverted or reversed, and finding objects is as simple as can be.

Why a Quick Finder instead of the Telrad? It is smaller and is in a vertical rather than horizontal format. That makes it a better choice for smaller scopes or for minimalist scopes like mine. It also offers something the unmodified Telrad doesn’t: the ability to pulse the reticle on and off, which can make it easier to position the reticle amid dim stars. If not always that easy if your skies are light polluted.

The bottom line is that a Quick Finder or a Telrad or any zero-power (“unit power”) finder can be difficult to use in suburbia. Oh, some parts of the sky, areas of the sky where there are plenty of stars to lead you to your targets, are easy enough. But spots like the region between the “arms” of Virgo that are star poor can be difficult. You really want to have an optical finder (which will deliver more stars than your naked eye can see) to supplement your Quick Finder if your skies are not perfect. Unfortunately, there’s no good way to mount one on my 8-inch, but, as you’ll soon hear, I have a work-around.

What was on those TV tray tables? On one went my box of eyepieces. Whether you are observing in the city or in the country, eyepiece choice is an often complicated, potentially costly, and sometimes controversial subject. It is one that deserves a blog of its own some Sunday soon. For now, I’ll just say I plunked my old Orion eyepiece case down on one of those TV tables.

On the other table were my reference materials. My star atlases. If I wanted to go completely Old Fashioned, that would be a print star atlas. I did place one on the tray, a favorite, Sky and Telescope’s Pocket Sky Atlas, but that wasn’t all. There was also my netbook computer. It is a little thing, will go all night on its internal battery, and runs Deep Sky Planner and SkyTools 3 fairly well. I thought I might eventually round up my hallowed copy of the Herald Bobroff Astro Atlas, but I didn’t believe I was quite ready to give up those wonderful computer programs, and a little netbook seemed humble enough to satisfy my desire for simplicity.

The Sun was soon setting and we were ready to roll, I thought. First observation? How nice it was not to have to mess with batteries or AC power supplies and cables. I do need a battery to power the secondary heater on the 8-inch, but it felt like it would be dry enough that I wouldn’t have to worry about that, which is pretty unusual down here in mid-spring, and seemed to bode well.

Did Rod still have his mojo workin’? Could I still find objects by looking at a chart and positioning the finder reticle among the stars? I brought up the Messier list in SkyTools, peered around the sky a bit, and decided M37, the great open star cluster in Auriga, was a good place to start. It was beginning to sink in the west, but was not yet too low. “Hokay. It’s just a couple of degrees outside a line drawn between Beta and Theta Aurigae, and closer to Theta.” I positioned the scope and took a look in the eyepiece, my 16mm 100-degree AFOV job, the Zhumell “Happy Hand Grenade,” but no star nest did I see. Nudged around a little bit and, “There she is. Little more subdued than I thought it would be.”

Despite its relatively low altitude, the cluster still looked amazingly good. How could it not? It is one of the premier Messier objects. It didn’t look anything like it does from Chiefland, Florida, where it often resembles a globular rather than an open cluster, especially in a small piggybacked refractor, but it was still sweet. Even the reddish central star was obvious in the skyglow/moonlight.

So it went with M36, M38, M35, M82, and a few others. I was feeling good, friends. Pumped. I hadn’t lost it after all. Or I thought I hadn’t till I decided to take a gander at M51. M51 is not exactly going to put your eye out in suburban skies. But I’d seen it easily enough from a considerably worse location, the backyard of a house half a mile from Bel Air Mall. It was just two smudges in my 6-inch f/8 back then, in the early 1990s, but was visible. Surely it ought to be more visible on this Pretty Good Night in an 8-inch from considerably better skies.

Nope. What I saw was the dreaded Nuttin’ Honey. Took another look at the chart. Nudged around. Tried higher power (helps to spread out background sky glow). Nothing helped. The truth, I had to admit, was that M51 was in the worst of the light pollution, and its area is rather star poor anyway. If I’d had an optical finder, even a 30mm like on my old 6-inch, it would have been duck soup. But I didn’t have one. What I did have, though, were setting circles. I decided I’d use ‘em on M51 on the next clear night.

Setting circles on an alt-azimuth mounted telescope? Yep. People have been putting altitude and azimuth circles/scales on their Dobsonians since the telescopes first became popular. There are some catches, but fewer now than there used to be. Few enough that shortly after Pat and I finished our 8-inchers, we put circles on ‘em.

You can read the whole story here, but the gist is that I found a Cloudy Nights thread with links to .pdfs of degree circles. I had access to a large format plotter (work) and printed a couple of circles for our scopes, and Pat did a nice job installing them. He sandwiched the azimuth circles between the scopes’ rocker boxes and ground boards, gluing circles to ground boards, and cut windows in the rocker bottoms for viewing the scale. In retrospect, it would have been more convenient if we’d made the azimuth circle adjustable, for aligning it on zero, but it is certainly workable.

The altitude indicator was a lot easier; we didn't make them, we bought them. Larger hardware stores (like Harbor Freight) sell angle indicators (inclinometers), large dials with pointers to indicate the angle at which the base of the thing is tilted. They are equipped with magnets on their bases, and it was easy to mount ferrous metal plates to the “top” truss tubes of the scopes for attachment of the level. I later went on to a supposedly more better gooder solution with an electronic level indicator (also from Harbor Freight), but the thing used button cell batteries at an alarming rate, and I went back back to the original, simple, plastic, unpowered dial indicator.

What was the catch I mentioned above? Getting the alt-az coordinates for objects. Obviously, as objects move across the sky their alt-azimuth coordinates change—and surprisingly quickly. In the Stone Age of the early 1980s, we used programmable HP calculators to get alts and azes. Input an object name or an R.A. and declination and the calculator spat out altitude and azimuth for the current time. That worked, but those calculators were not exactly user friendly or inexpensive.

A little later, PC programs (for MS-DOS) appeared that would give you altitude and azimuth coordinates of objects. Today, almost any planetarium program for Windows or Mac will do the same. That’s not the perfect solution, though; that came about 15 years ago. Beginning with PDAs (Palm Pilots) and continuing on to smart phones, we now have hand held devices that will display the current altitudes and azimuths of thousands of objects.

A couple of nights after my initial foray, I gave the circles a go from the backyard. On this night, a big, fat Moon (sorry Diana) would likely make finding objects via the Quick Finder difficult, so I set up the scope with the circles in mind. That meant I leveled the telescope. If the scope base is not close to level, objects will be farther and farther “off” as you approach the zenith. When I am using the circles, the 8-inch sits on a little plywood platform with screw in/out furniture sliders in the corners.

After you are level, step two is calibrating the azimuth circle (altitude does not require any calibration). Point the scope at Polaris, and with it in the center of the eyepiece field, set the azimuth circle to zero. That’s where having a movable azimuth circle would be helpful. Instead, I set the scope to zero azimuth and nudge the base till the star is centered in the eyepiece without moving the azimuth pointer off zero. Not a big deal, really.

Alrighty, then. First object was M3, spring’s primo globular star cluster, which is located in a fairly star poor area. It’s always been hard for me to find, and that was made worse on this night because the area to the east-northeast is in the Airport Boulevard light dome. I dug my iPhone out of my pocket, brought up Celestron’s SkyPortal app (a free, basic version of SkySafari), hit search, entered “M3,” and requested “Info.” That got me the current altitude and azimuth of the glob.

I exercised reasonable care in moving the scope till the pointers were on the indicated coordinates. Be particularly scrupulous with azimuth. With the circle on the base, beware of parallax effects if you are not looking straight down at the pointer. The closer you get it to the indicated azimuth, the better your results will be, natch.

I inserted the 16mm Zhumell, focused up and had a look. At first there was no sign of M3, but a little staring brought it out. It was not centered, but was in the eyepiece; out toward the edge of the field. In the fairly bright sky background delivered by a 62x eyepiece, it was a little less than obvious. While it had taken a minute or two to look the cluster up on my phone, I was pretty sure it would have taken longer to find using the Quick Finder.

In the next half-hour or so, I did M36, M37, M38, M81, M82, M35, M65, M66, and, eventually, even M51, which was somewhat out of the light dome by the time I went after it. There was no doubt in my mind the analog circles were a time saver under poor conditions. Was everything in the field of the 16mm when I stopped? No. Probably because I wasn't always careful enough with positioning the scope. Still, whatever I wanted was always just outside the eyepiece field and quickly swept up.

One thing that would have helped the circles would have been a lower power, wider field finding eyepiece. But the catch is that in the sorts of circumstances where I’d need to use setting circles—an overly bright sky—lower power can make seeing objects difficult even if they are in the field.

Really, the only question concerning the Dob’s circles was “Do I really want to use them?” Would that be true to my desire for “simpler”? I decided they (or even the set of Sky Commander DSCs as on my 12-inch) would be. At times. A big attraction of my new observing mode is the relaxing experience of cruising the stars with a chart and a finder. With a Moon in the sky and no optical finder on the scope, however, that can be more frustrating than relaxing. I’ll use the circles when I need them.

What next? One thing that may be next is a 10-inch Dobsonian. Chinese Dobs in that aperture are surprisingly inexpensive today, and one would give me a little extra oomph in my compromised backyard. And do that while not being nearly as much of a pain to set up as my 12-inch. Stay tuned.

As for my visual observing agenda, I have a couple of reasonably serious projects in mind that I can execute both from the back 40 with the 8-inch or the proposed 10-inch, and from the club dark site with the 12-inch (sometimes, anyway). I am still feeling my way with this y’all, but I feel good, as if I have found a new lease on (observing) life.

Comments:
Great Sunday morning reading as always.I work in a school here in nyc,and a couple of teachers are very interested in getting their husbands a "better telescope then their childhood department store scope that they use occasionally. Of course I am partial to my point and shoot 12" dob.I can literally roll it out from my garage and "look up" in 2 minutes.That is how I end many of my evenings after coming home from shopping with my wife or some other function,I tell her ,"honey I'll be in in just a few minutes,I want to look at something".
So my advice to these women who want to buy their husbands "a better scope is to keep it simple.I am leaning them toward a 6/8 inch dob which can be had for a few hundred dollars .They are asking me many question that I am glad to school them on.....thanks again.
 
Yes, the Telrad does not blink. But you can add second party blinking kits to it.
 
Good read Uncle Rod. I'm sitting here on my back deck this Monday morning watching the rain come down. I only work Tues Wed Thur nowadays. We've had the worse observing weather in 2015 in Texas that I can ever remember. Rain and clouds all the time. I think we're experiencing a rather song La Nina.
 
Suggest you try adding a 50 mm finderscope and print up your deep sky targets as they would appear in the 50mm finderscope view. I use 8-9 magnitude stars in the finderscope star maps. Use the Telrad and sky chart to roughly locate where you need to be, and then use the 50mm finderscope and finderscope chart to locate the faint object. This gives you many more reference stars for star hopping to the deep sky object.
 
Hi Lyle:

Unfortunately, a 50mm just isn't going to work on the 8-inch. I'll certainly have one on the proposed 10-inch. What work's well for me is not so much printing as using the onscreen display of Skytools, a three paned finder window that has naked eye, finder (your choice), and eyepiece. :-)
 
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