Sunday, July 04, 2010


Night of the Green M42

I’m not known as a Dobsonian kinda guy, muchachos. I’ll admit most of my observing life has been spent using, dreaming about, and talking about Catadioptric telescopes, mostly SCTs. But that does not mean I haven’t owned a few Dobs over the years, including one from that first commercial maker of the simple alt-az telescopes, Coulter Optical.

Do you remember them? Coulter was a fixture in amateur astronomy all the way from the 1960s to the 1990s. Over three decades, owner Jim Braginton, a.k.a. “Jim Jacobsen,” took his tiny company, based in Idyllwild, California, from being a well-respected maker of semi-custom optics to being the more well-known, if sometimes derided, maker of big, cheap telescopes. By the 1980s, Braginton had settled into making his Odyssey Dobsonians, simple, loveable telescopes in apertures from 8 to 29 fracking inches.

I’d often admired Coulter’s scopes. Those I’d used, mostly 13.1-inch Odyssey Is and 17.5-inch Odyssey IIs, were undeniably impressive in a proletarian sort of way. I didn’t dream of owning one, though, till the night I encountered the new Coulter ad. Braginton normally ran the same small advertisement in Sky and Telescope and Astronomy every single month, and this one was almost the same as always, but not quite.

Not that Coulter never offered the different. At one point in the 80s, they were selling what had to be the most different, the strangest piece of astro gear this old boy has ever seen. Wanna turn your (Blue Tube/mirror box) Odyssey into an equatorially mounted telescope? Put it on the gadget seen at left. I mean, can y’all imagine trying to manhandle the 13.1-inch Coulter onto such a thing? Keeping it there? Moving it around the sky without braining yourself or somebody else? I sure can’t.

But, yeah, the ads were the same month after month after month, showing the same old lineup of Odysseys, all with f/4.5 focal ratios: 8-inch, 10-inch, 13.1-inch, 17.5-inch, 29-inch. When the 80s faded-out, the original Blue Tube Coulters, including the massive 29-inch—which looked more like an outhouse than a telescope—went with ‘em. All except the discontinued 29 devolving into the cheaper-to-make Red Tubes (no mirror box). From that time on, Coulter’s product-line appeared pretty much set in stone. Till Jim threw us a little curveball.

‘Twas a quiet and cloudy evening back in late winter of 1993. I was browsing the just-arrived copy of Astronomy, idly flipping pages after a long day in the shipyard. I didn’t much feel like reading yet another Astronomy epistle on the wonders of blackholes, so I began exploring the magazine from back to front as was my usual and admittedly strange wont back then. Turned a page or three, and there was Coulter’s usual single column ad for the Odysseys. I started to move on, but stopped. Something diff’rent here...

What was different was the addition of a new telescope, an 8-inch. Yes, Coulter had been selling an  8-inch Odyssey for years, but not this 8-inch Odyssey. The new 8-incher (the old one was still there, too) had a larger focal ratio, f/7. Ever since I’d sold my not so hot Celestron Super C8 Plus to help finance a divorce, I’d been looking at Coulter’s ads with more than casual interest. I wouldn’t have minded having an 8-inch telescope of some kind to supplement my Palomar Junior and ATM 6-inch Newt while I got the pennies together to purchase the latest and greatest from Celestron.

Braginton’s 8-inch f/4.5 didn’t seem quite the scope for me, though. That short tube perched on the small rocker box didn’t look overly practical. Portable, yeah, but unless you were the size of GI Joe, you’d have to rig up something to set it on, which would have to be lugged around with the telescope. And I’d have to do a lot of lugging to avoid the trees in the yard of my current domicile.

Squinting at the tiny picture, actually just a silhouette, I could see the new 8’s naturally longer OTA was supported by a taller rocker box. That was good. What was better was the price. It was almost unbelievable. Jim was selling the thing for $239.50 (plus shipping, of course). This was long before the Chinese telescope price revolution, and even today less than 250 bucks for a working 8-inch telescope is pretty dadgummed impressive. I was convinced. I wrote out a check, including a little extra for a Telrad base. Coulter didn’t include a finder, though the Odysseys did ship with a single eyepiece. I then settled in for what I figgered would be a long, long wait.

You can scarcely imagine my surprise when the 8-inch showed up on my doorstep not more than a month after I mailed the check (this was just before the cotton-pickin’ World Wide Web, younguns). Back in the mid-80s I’d conceived an ATM project that would involve a ten-inch Newtonian OTA, and noticed Coulter was selling 10-inch f/5.6 primary mirrors for an astounding $129.50. A quick call to ‘em, however, elicited the information that the wait time on these mirrors could be up to two YEARS. I didn’t expect to wait that long for the 8-inch f/7, but I suspected it would be “months” at least.

Once I extracted my new telescope (is any phrase in the English language more wonderful than “my new telescope”?) from its big and slightly battered cardboard box, it was rubber-to-the-road time. The Odyssey was fully assembled, and the first thing I noted was that it was one heavy mutha. The red Sonotube was thick, very thick, darned near a quarter of an inch thick. It was mated to a tall rockerbox made of naturally heavy particle board, which was equipped with three 2x4 “legs” on the bottom to keep the scope from toppling over. Not exactly “grab ‘n go.”

The OTA was crude but reasonably attractive. The fire-engine red thing was actually nicely finished and was equipped with a plastic end-ring up front. The mirror cell was a very simple push-pull affair, nothing more than a couple of particle board disks, with the thin plate-glass mirror RTVed and duct-taped in place. This cell was thoughtfully equipped with three plastic feet, so you could safely stand the OTA on end while moving the scope outside in two pieces. The secondary support was the same thing Coulter had been using since 1980, a single, thick strut that was only minimally adjustable. The main bring-down was the focuser.

If you could call it that. In Coulter’s earlier Dobsonian days, the Odysseys were equipped with not overly fancy but perfectly serviceable rack and pinion focusers. If you’ve been in the amateur astronomy game for a while, think of the focusers Old Man Novak used to sell. By the 1990s, Braginton had had to cheapen up the scopes. Not only had the mirror boxes disappeared, so had the focusers. What all the Odysseys had by the time I got mine was “focusers” made of plumbing parts and 1.25-inch aluminum draw tubes. The design was workable, with a threaded ring that could be tightened to adjust the focuser’s “tension” as you pushed it in or pulled it out to focus, but it shore wasn’t “elegant.”

Howsabout the rockerbox, the mount? I’ve often described its particle board as looking like it was cut out with a chain saw. In truth, it was a little better than that. At least some attempt had been made to sand it and round off sharp edges and corners. Even had a couple of handles. If only the altitude and azimuth bearings had been a little better.

As most of y’all know, the combination of bearing materials that yields smooth and “stiction” free movement is Teflon pads riding on Ebony Star Formica. The Odyssey 8 was about as far from that as you can get. The bearing pads appeared to be Nylon, maybe some kind of closet door runners. The particle board altitude bearings, which were too small, about 6-inches in diameter, were covered with vinyl, some kind of trim material, perhaps. The azimuth bearing was a square of vinyl floor tile. The remarkable thing? The movements were OK—after the application of a little Pledge furniture polish, anyhow. Maybe because the long and heavy tube provided plenty of leverage as I nudged it along to track.

And that was almost, but not quite, it. In addition to a couple of pages of instructions written in Jim’s charming style (“You’ll get to see METALLICBURST NEBULAS!”) there was a single eyepiece, a 25mm Kellner. Where it had come from was immediately obvious: there was a diopter scale on the barrel that let slip its binocular eyepiece heritage. Survey of the Odyssey completed, all I had to do to prepare it for First Light was stick-on the TELRAD base and wait for dark.

The sky was somewhat clear that night, which don’t mean I totally escaped the fearsome and very real New Scope Curse. There was substantial clear sky to the south and west, but the cloud gods, obviously having detected the presence of the new Odyssey, were marshalling their forces in the East. Luckily, there was a sweet young Moon to the west who would at least allow me to make sure the scope wasn’t punk—or junk.

Over to Luna, then. How did she look? She looked good, but she didn’t look downright special. Why did I expect “special”? By the early 90s, short, fast Newtonians had become de rigueur. It was now unusual to find an 8-incher with a higher focal ratio than f/6, and I reckon I, like a lot of y’all, had developed misplaced expectations as to THE MAGIC OF LONG FOCAL LENGTH REFLECTORS.

Sure, the long-tubers are easier on the eyepieces than shorter ones, which was a good thing, since in 1993 I was still using Kellners, Orthoscopics, Erfles, and the odd Konig, but otherwise…an 8-inch is an 8-inch. Frankly, contrary to what you may have been told, medium-fast mirrors are actually easier to make well than slow ones. How did the Odyssey’s test out? The star test, given the not-so-hot seeing, looked alright; decently well-corrected, though maybe not quite the 1/8th-wave the ads promised, with maybe a touch of turned-down-edge. I’d seen worse. The Moon looked good, as did Venus and what I could see of M3 when it cruised into a sucker hole. I figgered I’d got my $239.50’s worth however you sliced it.

Certainly, the Odyssey did exceptionally well on the deep sky. It gave me a wonderful view of that spring's bright supernova in M81. Later in the year I had a ball with the scope at the 1993 Deep South Regional Star Gaze—during the few clear hours we got, anyway—effortlessly hopping from one Pegasus galaxy to the next with only the aid of the TELRAD. Course, our old site, Mississippi’s Percy Quin State Park, was still reasonably dark, and my eyes (and my patience) were better than they are now.

The Odyssey also proved her mettle as a public star party telescope. Yeah, her long, long tube was a bit of an impediment for the wee-est of the wee folk, but a little step stool took care of that problem for most of ‘em. One thing was sure: the telescope, with her massive particle board mount and thick, thick Sonotube, was well-suited to endure the eager, sticky hands of the Lollipop Guild. Hell, it would probably have taken at least a 10-megaton H-bomb to faze “Mabel,” as I’d named the Odyssey for some reason. Maybe because the name seemed to fit a telescope that was plain, but sturdy and reliable.

One of my fondest memories of Mabel is the night she met Miss Dorothy for the first time, in 1994. Shortly after we’d begun dating, I’d broken the news to Miss D. that I was an amateur astronomer. Fortunately for me, she wasn’t overly disturbed by that odd confession. I suspect because, in her innocence, Dorothy thought that meant I had a little refractor I’d pull out to look at the Moon once in a while. She did seem a little surprised when, in answer to her question of where I was taking her for our Saturday Night Date, I responded: “To Saint Luke’s Church, where we are gonna show the sky to fifty Boy Scouts.”

Dorothy bore up well. In fact, she was positively taken by the view of Jupiter through Mabel. I’d pronounced it, “not bad, OK,” but she thought Jupe was beautiful. She didn’t just look, either; D., who started her career in education as an elementary school teacher, did yeoman duty managing the crowd of excited Scouts, a good thing, since only one of my fellow PSAS members had made it out that night. Afterwards, on our way to Cucos, my then-favorite Mexican restaurant--till I discovered El Giros, home of the bottomless Margarita--Miss D. turned to me, smiled, and said, “We did good, didn’t we?” Things were definitely looking up for (not so) old Rod.

That’s, in typical Unk fashion, getting ahead of the story, though. About five months before I was introduced to Miss D., I was feeling kinda bored. Things were slow at work, and the divorced life still seemed a mite strange. Well, I could always read, and, thanks to the late, lamented Astronomy Book Club, I had a volume or two coming in every month. This month’s selections had been kinda thin: lotsa gee-whiz beginner-oriented astronomy-fact stuff and not much in the way of amateur astronomy. Almost on a whim, I’d ordered the only amateur book that appealed, the First Edition of Michael Covington’s Astrophotography for the Amateur.

Which is a flat-out wonderful book, and, today, in its Second Edition, it is just as useful for beginning imagers as it was two decades ago. I should probably devote a full blog entry to it someday, but for now I’ll just say, “Get it if you are starting out in celestial picture taking.” The remarkable thing, though, was not that I’d found a good book on astrophotography—by the early 90s there were plenty of them—but that after my frustrating, near disastrous attempts to capture Comet Halley in the eighties (I'll tell y'all that story some Sunday) I was willing to try astrophotography again. So soured on the art had I been that I swore I'd never look through another guiding eyepiece.

But, yeah, the bug had bitten again. I was anxious to get out under the stars with a camera and into a darkroom with an enlarger. Too bad I didn’t have a scope suited for astrophotography. With my Super C8 Plus gone, I had only the Pal Junior, my home-brew 6-inch Dob, and the Odyssey. I had no desire to essay more fuzzy shots with my Pal. But could I take any kind of pictures with Dobsonian mounted Mabel? Maybe. How about some nice Moon pictures? And wouldn’t you know it; Urania provided me the perfect opportunity for that very thing right away: the total Lunar eclipse of November 28 - 29, 1993.

Moon pictures! Yay! But how? Actually, a series of “hows,” the first being how to mount the camera, my heavyweight Petri FTII SLR, on the telescope. There would be no way to lock down either axis, this being a Dobsonian, and since the Petri was near-bout battleship heavy, cobbled together balance weights might not suffice, either. Hokay. What if I shot just like I had with my 3-inch Tasco Newtonian and my Argus Seventy-Five all those long, long years ago back in 1965?

While the Tasco’s little alt-az mount could be locked down in altitude, I didn’t have money for any kind of camera mount and would have been reluctant to drill holes in the telescope’s pretty white tube even if I’d had the money. Instead, I just set the camera up on a tripod next to the scope. With an alt-az mount that works pretty well, since the focuser remains at a constant angle no matter where you are pointed in the sky. If you’re shooting afocally—lens remains on the SLR and points into the eyepiece—there’s not much worry about stray light entering the camera as there would be if you tried to shoot prime focus (no lens). I rounded up the old Arrow tripod I’d inherited from my Old Man and started hunting for the Petri’s cable release.

Without success. A cable release, a “remote release,” is vital for Solar System imaging the old-fashioned way, with film, in order to minimize the vibration that will inevitably result from your finger pushing the shutter release. I’d hop down to the local camera emporium and buy a new one. The good folks at Calagaz Camera stifled waves of laughter at the sight of my old (e’en in 1993) Petri and took a look at its shutter button. “Non-standard” they pronounced, “sorry.” Not to worry; I had another idea. The camera’s self-timer worked fine and using that would allow button-pushing-induced shakes to die out before the shutter opened.

Sunday evening’s eclipse was very nice and even unusual. It was dark overall, but one limb, the southern limb, was oddly bright. Some observers likened this to the “diamond ring” phenomenon of a solar eclipse. Weird! Wish I could say my pictures were unusually good, that they were e'en in spitting distance of the beautiful eclipse photo on the cover of Mike Covington's book. They, like the one below, do show a hint of the Earth’s shadow and the bright limb, but in truth they were really not much better than the shots I’d done with the Tasco as a little kid. I did enjoy setting up the darkroom junk again after a hiatus of some years—I miss the smell of Dektol and hypo now. The eclipse itself was not what generated enduring memories of this observing run, howsomeever. What was was the title of this blog entry.

I can tell you why I bothered to look at M42 on a Full Moon night: I was bored. The umbral phase was not due to begin until well after 11pm, but I’d been champing at the bit since sundown and had dragged Mabel and the associated gear out into the front yard shortly after nine. Without much else to look at in the Moon-washed sky, I figgered I’d give bright Orion, who was riding high, a quick peep before blowing out what little night vision I had acquired.

We’ve all heard tales of “color in M42,” mostly concerning Big Dobs at dark sites. And, actually, it is possible to see some color in the Great Nebula with a large enough scope and pristine enough skies. M42 has a nice, high surface brightness, relatively speaking, and can at least barely stimulate the eye’s color sensors, the cones. Still, color in M42 is usually subdued: pale greenish/bluish tints not unlike the visual appearance of some planetary nebulae. A real bigdob can also show signs of the red in the nebula, which is tough for the human eye to perceive even at the brightness of M42. Usually, these reds look more “brown” than “red.” I’d seen these things in buddies’ large telescopes at star parties, but never had I been sure I had seen any color at all from an 8-inch at any site. That was about to change.

What the Green M42 Affair reminds me of is the time I saw the Ashen Light of Venus (coincidentally, with the very same scope, whatever the heck that means). The second I put my eye to the 25mm (Vixen) Kellner, it was obvious. There was no guessing or head-scratching. M42 was GREEN. I don’t mean faint hints of color like in the Saturn Nebula or the Blue Snowball; I mean g-r-e-e-n, like a consarned stoplight. I looked around in bafflement, wondering what was going on. Was the danged Air Force playing Starfish Prime again? Whatever the cause, the effect remained visible with different eyepieces, even at fairly high magnifications, until it was time for me to get going with my Moon pix.

If you use your imagination you can see this was an eclipse.
I wondered about this odd incident a lot over the years. I was convinced what I’d seen was at least as “real” as the Ashen Light, but the amateurs I told the story to were either skeptical, or thought I was pulling their legs, and after about a decade passed and the mental image of the limeade nebula began to fade, I started to doubt what I’d seen. Till one night I saw it again—if maybe not in quite such pronounced fashion—this time with my 12-inch Dobsonian. What did the second night have in common with the first one? It would seem “not much.” Larger aperture telescope. Different and much superior eyepieces. Ah, but the conditions were similar, a bright near-Full Moon in the sky not far from Orion.

I’ve hunted for similar reports, but without success. Oh, plenty of people see at least hints of green in the nebula with 8-inch and smaller scopes, but I haven’t found anything that mentions a Full Moon being in the mix. Dunno. Maybe I’m the only goober who looks at Orion on a Full Moon night.

Why should a bright sky background and a lack of dark adaptation make it easier to see green in this DSO, anyhow? Does the lessened contrast between nebula and sky have somethin’ to do with it? Or is it the result of the suppression of the eye’s dark adaptation? Does either thing make a lick of sense? Prob’ly not, and y’all can no doubt tell my knowledge of biology and anatomy is like Sherlock Holmes’ knowledge of philosophy and literature—NIL. If you’ve had or heard of similar experiences, or have a better explanation than mine, I’d very much appreciate hearing from you.

So…what happened to Coulter? Coulter, in the form of Jim Braginton’s company, pressed on till the mid-1990s despite increasing competition from the fancier mass-produced Dobsonians of Meade and Orion. When Jim’s health began to fail, Coulter began to falter, closing its doors shortly after his death. The 8-inch f/7 continued to sell right up till the end, and they are still fairly common on star party fields.

What happened to my Coulter? I continued to use Mabel into the late 1990s, at least as my public outreach scope and as a semi-grab-‘n-go rig. But eventually she was gobbling less and less starlight. I’d decided I needed a real grab ‘n go scope, something I wouldn’t mind carrying into the yard at the spur of the moment. That was possible with the Coulter, but only just. I found a little Short Tube 80 refractor on an EQ-1 mount fulfilled that need better, and was capable of showing me purty much anything I cared to see on grab-‘n-go nights. When it came to the public/kids, I eventually concluded the primary requirement for a public outreach scope is a drive. Having to nudge-nudge-nudge between “customers” is a pain.

Mabel was relegated to Chaos Manor South’s massive equipment vault, where she proceeded to gather dust for a few years. Till I had a brainstorm. My brother-in-law had often expressed an interest in amateur astronomy, but had no scope. Mabel deserved some time under the stars. The old scope now lives in Boulder, Colorado, where I hope she is enjoying clear mountain air and many photons. She deserves it.

She deserves it because, despite her plain simplicity, there was something there beyond that humble exterior. She had a personality, a certain ineffable je ne sais quoi, and she saw me through those lonely months before I met the wonderful Miss Dorothy.  One thing's sure:  $239.50 ain’t much to pay for both the Ashen Light and a Green M42.

Next Time: 'Twas a surprisingly nice night last night. Clear most of the time and amazingly cool and dry. That means H-e-r-s-c-h-e-l-s and an update to the good, ol' Project next week.

I once looked at the Orion Nebula with the 26" f/4 Newtonian at the NJAA observatory in High Bridge, NJ. The nebula was, as you say, green as a traffic light. Someone suggested that there may have been a nebular filter or a green filter in the eyepiece. I don't know, but I never saw it that way again in that or any other scope.

One year at the Winter Star Party I went around annoying people by asking to look at the Orion Nebula so I could see if I could see color. Even in the 36" "Yard Scope" there was little more than a trace of color around the edges, though I did notice that the E and F stars in the Trapezium showed color (reddish) in that scope.
Dear Uncle Rod,

Thank you very much for this story, and especially for the wonderful simulated image at the top of the page. It at once revived the memory of my own best view of the Orion Nebula. That was also the first time I saw the contrasty structure of the “outer loop” (the part of the nebula which is toward south-south-west), and it was this part, not the brightest part of the nebula, that was green. The hue in your simulation is pretty much exactly the kind of green. It was on a mountaintop (some 1500 m, grey or black on the light pollution map) after a violent autumn storm front had passed. The transparency was the best I have ever seen, Mauna Kea excepted. I used mounted 100-mm binoculars (an f/8 “binoscope” made by Astromeccanica and LZOS) at 33x without any filters. The Orion Nebula was supposed to be a quick test object, but I stayed on it for what was left of the night after it had cleared, and have not seen it like anything close to that since. The color that I saw would probably be obtained by desaturating your simulated image to one-half, i.e. what would remain would still be rather grotesquely saturated.

In the context of your discussion of commonalities between your two “green M42” nights I should mention that in my case the Moon was down. Orion was not yet high and the sea-level astronomical twilight was an hour away, but that area of the sky nonetheless appeared very dark in the beginning. Later with its brightening the color was completely gone before the outer loop became washed out. A credible physiological explanation of why brightening might help does not immediately come to mind of this physiologist, but he is not an expert on sensory systems. Very intriguing!

Ivan Maly
Dear Uncle Rod,

O’Meara writes in his Caldwell Objects this about Barnard’s Galaxy: “Oddly, but as the last-quarter Moon began to rise one night while I was looking at NGC 6822, the galaxy seemed to pop into view with sharper clarity at 23x and take on a pale green tinge. Is this another optical illusion? Or did the background Milky Way fade away under the moonlight to reveal the galaxy?” I tried this last night under similar conditions, but saw no color.

Ivan Maly
Hi Ivan:

Curiouser and curiouser...

Odd, I've never had much trouble seeing the green in M42. I see it clearly in my 20x80s, my 6", my 8", and the Z12 dob. Until I read this blog post, I just assumed seeing the green was common.

Maybe my eyes come pre-pickled or something. Regardless of why, it's sure pretty.
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