Sunday, December 08, 2013

 

My Favorite Fuzzies: M5


The frigid winds of approaching winter—as frigid as they get deep in the southland, anyway—are buffeting good old Chaos Manor South. It’s time to think about good little Christmas trees and ho-ho-ho and mistletoe and presents to pretty girls, muchachos. But this Sunday, let’s cling to blessed summer just a while longer with a visit to my favorite globular star cluster.

Y’all have probably already glommed onto the idea that that ain’t M13, given the title of this Sunday’s installment. Despite Unk’s life-long love affair with Herc and the countless hours he spent chasing the glob’s stars as a sprout, it’s the neighboring cluster, M5, that won his heart. Actually, it’s maybe partially because I spent so much time trying (fruitlessly) to resolve stars in M13 with my Palomar Junior 4-inch as a little person that M5 displaced it in my affections.

Hokay, let’s get started as we usually do in this series with the just-the-facts-m’am concerning Messier 5. M5, a.k.a. NGC 5904, is a magnitude 5.7 globular star cluster in Serpens Caput that is 23’ in diameter. That makes it a little brighter and a little larger than M13. It is, surprisingly, also easier to resolve in a small telescope than Hercules despite the fact that they both have a Shapley-Sawyer (concentration) Class of V.

M5 is one of those (numerous) Messiers not discovered by old Chuck himself. Its first recorded observation was in 1702 by a German astronomer and calendar maker, Gottfried Kirch. Charles didn't get the star cluster in the field of his small refractor till 1764, and didn't know it was a star cluster when he did, recording it as a “nebula without stars.” It took our old buddies Will and Lina Herschel to resolve M5, which they did with their famous “20-foot” scope, counting over 200 suns there in 1791.

That’s just scratching the surface, of course. M5 is home to at least 150,000 stars. It is not only incredibly rich; it’s one of the larger of the Milky Way’s globs, being about 165 light-years in diameter. It is also very old, 12 to 13-billion years, and must have been witness to the titanic events that shaped the Milky Way. Like all globs, it is in an elliptical orbit around the galaxy’s center, and at this time is an estimated 24,500 light years from our cozy little rock.

So, what’s my history with M5? I know good and well I observed it and no doubt recorded it in my log back in the 1960s. Probably even made a drawing of it. Unfortunately, most of my early logs have been gone a long, long time; the only drawing I’ve got left from the early days is one of Copernicus I discovered in a box of papers I found in Mama's house after she passed.

You’d think I’d have some memory of my first sight of such a glorious cluster, and I do, but just barely. I vaguely remember checking it off the Messier list along with M10 and M12 one long ago summer’s night. Dadgummed if I can remember what it looked like or what I thought of it, though. It obviously didn't make much of an impression, and I wonder why. Not because it wasn’t well placed for observing; down here, it is good and high all spring and summer long. There is the weather, though. Maybe the haze took it down a couple of notches. Or maybe I didn't think it was that good in my Pal Junior because I didn't know it was supposed to be that good. If I wasn’t convinced what was in my eyepiece should be spectacular, I had a tendency to just glance at an object and move on.

The few astronomy books in my minuscule library—Stars, Norton’s Star Atlas, The Amateur Astronomer—probably said M5, was outstanding, but they had a tendency to say that about all the Ms, even those I couldn’t see, like M101. They didn't take into account what a little feller with a little scope trapped in suburbia had to face. Even at the tail end of the 1960s, there were plenty of streetlights, and the new shopping center, Bel-Air Mall, had purty much put the kibosh on my eastern sky by the end of the decade.

I no doubt looked at M5 plenty of times in the years between the 1960s and the 1990s when I owned plenty of respectable telescopes, but I didn't really make friends with the top kick glob till one night in the early 90s when I set out to look at Ophiuchus’ M10 and M12, just like I had on that night in the 60s.

It’s been a wonderful two decades (almost) with my lovely wife Dorothy, and 1993, the year before I met her, seems a long time ago. I do have one clear and good memory from what was a slightly lonely time for me. I was house-sitting for my vacationing brother and sister-in-law in July of that year. I don’t know that they really needed a house sitter for their suburban digs; maybe they just thought a change of scene might perk me up.

As I’ve written before, at this time I was between SCTs. All I had other than the good old Pal Junior was a 6-inch Dobsonian with a Parks primary I’d cobbled together in an afternoon or three. It wasn’t much, but it was way better than nothing. When I have a telescope and a clear sky, there is no way I feel lonely, and I’d brought the sixer along (never did get around to giving her a name) for my sojourn at Danny and Pam’s.

Dark came and clear sky with it, and I was out into the backyard with the scope in a right quick hurry. Once the neighbors’ dog, who wondered what the hell I was doing, got over his suspicions and shut up, it became a calm and quiet if somewhat warm and humid evening as is the rule down in the Swamp when summer is in full swing.

What the heck would I look at? I hadn’t visited Ophiuchus yet this season, and I figgered M10, M12, and some of the other globulars in the cluster-rich serpent-bearer would make good fodder for the column, “From City Lights to Deep Space,” I was doing for the Possum Swamp Astronomical Society’s little newsletter. The City Lights articles would eventually form the basis of a book, The Urban Astronomer’s Guide, after the turn of the century, but in 1993 that would have been unimaginable to Unk. I was just havin’ fun writing for my fellow local amateurs and had no greater ambitions for my little articles than that.

I spent quite a while going back and forth between M10 and M12, since one of the things I wanted to emphasize in my column was how wrong people are when they call the two clusters “the twin globulars.” They are close together, sure, barely three and-a quarter degrees apart, but they couldn’t look more different. M12, a Class IX glob, is much looser than M10, a VII, which looks more like a “normal” cluster along M13’s lines.

When I was done with the pair, I almost headed for M107, but it’s such a pitiful little thing in suburban light pollution that I demurred for the moment. M5 would be good and high and it was always easy to find, making a triangle with prominent Delta and Epsilon Serpentis.

Once I had M5 in the field of my prized Vixen 12mm Orthoscopic? On this hazy night, with this small telescope, in the suburban light pollution, I was near blown off my feet. Despite the conditions, it was clear this was a big ball of stars, especially when I bumped the power up to 200x. The core was grainy and slightly elongated, and the periphery was a mass of the tiniest stars you can possibly imagine.

Hell, this thing looked almost as good as M13. Maybe even as good. I zipped over to M13 to check. Nice…but…M5 seemed brighter despite its slightly larger size. And it was better resolved in the 6-inch. I wasn’t quite ready to say my old love had been replaced, but almost.

I continued looking at M5 periodically after that night, always marveling at it, but my definitive view didn't come till almost five years later in the spring of 1998.  A lot had changed in those five years. Not only did I have a lovely new wife, I had a pair of new telescopes, a Celestron Ultima C8 (Celeste) SCT and a 12-inch Meade StarFinder Dobsonian (Old Betsy). Of the two, Celeste was getting much more starlight despite Betsy’s downright exquisite optics. The reason was that I couldn’t use the 12-inch at a dark site.

Miss Dorothy
When I first got Betsy I did use her out in the dark. Not only at various local observing venues, but at the cotton-picking 1997 Texas Star Party. That was the last time she got out of the city lights, though; after that she was relegated to Chaos Manor South’s backyard.

The reason was Unk’s automobile, a Toyota Camry. When I’d first bought Betsy, I had a little Hyundai Excel hatchback. Almost unbelievably, due to the Excel’s hatchback nature, I was able to stuff Bets in that roller-skate of a car. So, all was well until the Excel’s engine gave up the ghost in rather dramatic fashion one afternoon when I was on the way home from the shipyard. Though I tried and tried, there was simply no way the near water heater sized Sonotube was going in the Toyota.

At first I was OK just using Betsy in Chaos Manor South’s backyard; she allowed me to do my first good videos of Jupiter (with a handheld camcorder), and it was pretty amazing what she could pull out of the Garden District light pollution. I wouldn’t have have thought it possible, but the StarFinder was able to resolve M35’s little companion cluster, NGC 2158, in the sodium-orange skyglow. I was happy with the C8’s visual performance under dark skies. Usually.  But sometimes it would have been nice to bring a little more horsepower to bear on the tougher faint-fuzzies.

I eventually talked the situation over with my friend and ATM, Pat Rochford. I sure wasn’t hinting he should take on the sizable task of rebuilding Betsy into a more portable form. I just wanted his thoughts on how I should proceed. Should I sell the scope and look at an upscale truss tube 12-inch, maybe? I couldn’t convert Old Bets to a truss scope myself, that was dadburned sure. Unk + hammer + nails = disaster. Despite my protests, however, Pat insisted on taking on the job of converting Betsy to a more portable truss tube configuration. I felt guilty, yeah, but Pat insisted he was in the mood for a big ATM project.

My part in the rebirth of Betsy was mostly just acquiring telescope parts: a mirror cell, pivot bolt, and a few other things from Randy Cunningham’s AstroSystems; and a focuser from Jim’s Mobile. The only part that took a while to arrive was that NGF-3 Crayford from JMI. It was well worth the wait, however. While the focuser ain’t fancy by today’s standards, it is smooth and precise and has just kept on working year after year. I needed Ebony Star Formica for the bearing surfaces and a Telrad base, too, and I got those from Crazy Ed Optical, my (now sadly gone) go-to telescope parts guy back in the 1990s.

Pat and New Old Betsy...
In addition to the genuine scope junk, I needed a few things I could get in town, starting with plywood. I bought the best grade I could find at Home Depot. It wasn’t perfect, but was more than sufficient without lots of voids and other problems. I found a source for Kydex plastic for the upper cage assembly at a local plastics supplier. Finally, by hitting every Ace Hardware in the area I was able to buy enough aluminum tubes for the scope’s truss and the upper cage assembly.

Pat did most of the work at his house, but I did get to participate in the project’s christening, the initial cutting of the plywood out on the back deck of Chaos Manor South. In other words: “And I helped.”

Once in a while Pat would consult with me about design choices; the major one of which was how we would attach the aluminum truss tubes to the upper cage and mirror box. By 1998, most truss tube Dobsonians were using clamp-blocks to secure the truss tubes. I told Pat I would be fine if we did things the old-fashioned way, fastening the aluminum tubes with bolts and wing nuts. That would simplify Pat’s job considerably, I thought. The scope, a 12-inch f/4.8, was short enough that I didn't think that would make the scope difficult to assemble, either.

Amazingly, by the time I had the last of the scope parts in hand, Pat was dang near finished with the major work and all that remained was cutting the truss poles to their proper lengths. We would not be able cut them long and slide them in and out in clamp blocks for testing, so cutting them to exactly the correct length was critical. That’s where the fabled Picnic Table Telescope came in.

We secured the mirror box to one end of Pat’s wooden picnic table in his backyard, fastened the upper cage at the other, tilted the table up at the stars (!), and began checking eyepiece focus. Pat’s wife, Stephanie, clearly thought we’d finally flipped out, but the Picnic Table Telescope worked crazy good. We were able to position the upper cage exactly the correct distance from the mirror box so all my eyepieces from the Nagler 12mm on the “out” side to older Vixen eyepiece on the “in” side came to perfect focus. Pat was able to measure the distance for the tubes easily, and I have never had a problem bringing any ocular to focus in Bets.

What was Betsy like when she was finished? She was a completely different girl. The only things we reused from her original Sonotube configuration were the primary mirror, secondary mirror, secondary holder, and spider. I thought the new scope was beautiful and elegant in a simple, functional way.

Chart done with Coelix...
All that remained was first light for New Old Betsy. In a nice bit of synchronicity, the telescope's completion coincided with an invitation Pat and I got to observe at the dark site of the Escambia Amateur Astronomers Association over in Pensacola. Since the PSAS was without a decent observing location at this time, I thought this would be the perfect opportunity to put New Old Betsy through her paces.

When we made it to the EAAA dark site, a farm up in the Florida panhandle that belonged to one of their members, I found getting New Betsy set up was a little harder than before. Not bad, but admittedly more work than getting her Sonotube body ready to go. The flip side of that was that I would not have been able to set the scope up at a dark site in her old form.

After Bets was assembled, I took her for a quick spin in the gloaming, just pushing her from one horizon to the other. Pat had done a beautiful job, and the Ebony Star Formica and Teflon bearings were so much smoother than the Nylon on smooth Formica of the old Meade mount. I did notice motion in altitude was actually a little too easy. With lighter eyepieces, the tube tended to drift upward at some altitudes. I fixed that later with a small weight on the upper cage and I’ve never had another problem of that sort. I guess that’s the hallmark of Old Bets:  “Never a problem; just works.”

Time to get going. In went the 12mm Nagler and to the Telrad went my eye. What would be my first light object? I’d thought that might be M83, the lustrous Hydra spiral galaxy. But on this early spring evening it was still way low even as astronomical twilight came in. What then? “Oh, yeah, M5.”

I didn’t preserve that observation of M5 with a log entry or a drawing. Wish I had, but I was too excited about taking first light with a “new” telescope. Didn’t need to, anyway. The way that great globular star cluster looked is locked into my mind even to this day. M5, riding nice and high, was an incredible forest of suns filling the 12mm Nagler’s 82-degree field. The core was burning bright, but was clearly made of countless tiny stars, and the hordes of them outside that core stretched all the way to the big field’s edge. The overall color of the cluster was a faint sapphire blue, but orange-yellow suns sprinkled here and there across the lustrous globe of stars winked in and out.

I just kept looking and looking at M5, occasionally slewing over to M13 for a comparo, but always coming back. M13 was glorious, sure, but M5 was better. I finally got to M83, which was also spectacular as the night grew older, but this was the night of M5. If I hadn’t seen another blessed thing with my wonderful scope, that would have been enough.

I wasn’t shy about proclaiming my preference for M5 over M13 after that night, either. I thought I might get some guff from my article in a long-ago Amateur Astronomy Magazine article where I proclaimed M5 the King of the Northern Globulars, but I didn't. Unlike the time (then) Amateur Astronomy publisher Tom Clark and I pointed out that large aperture Dobsonians really don’t need mirrors even as good as ¼-wave, most folks, those who knew M5, tended to agree. How could they not? It’s a close race between the two globs. Close, but no cigar for M13.

What’s happened with Betsy over the years? I’ve continued to use her, if not as much as my CATs, including for a pair of weeks of incredible deep sky voyaging at the 1999 and 2001 Texas Star Parties. She did get further refits, too. First time around, Pat and I upgraded her to a smaller secondary mirror, a secondary heater, a better secondary mount and spider, and a set of Sky Commander Digital Setting Circles. It was also at that time that I also had her primary recoated with Spectrum’s top of the line high-reflectivity coatings.

Alas, Betsy still didn't get used as much as she should. One reason for that was the substantial weight of her old-school mirror box. A little over a year ago, Pat shaved some pounds off the scope’s big rear end (sorry Bets) and that helped. Bets still doesn't get used at home—those trees—but she does get to the club site once in a while. I hope that once Dorothy and I move out to the suburbs she’ll get the full ration of starlight she deserves.

One cautionary note I have for those of y’all considering a first 12-inch Dobbie:  In this aperture, a Sonotube is much easier to deal with at home than a truss of any kind. Manhandle the rocker box into the backyard, plunk the Sonotube tube in it and you are ready to observe. A truss? Depending on your doors and other obstacles, you may find a truss scope may need to be disassembled for transport to the backyard. You will not want to do that on a regular basis, believe me.

M5? That big star cluster shines on like that crazy diamond it is, and I admire it every spring and summer. One thing I realized in the course of writing this? Despite my love for the glob, I’ve never taken a decent picture of it. There’s one quick and slightly out-of-focus shot done with my old Meade DSI, but that is it. I promise to rectify that in the spring, and the anticipation of that will help carry me through the clouds and cold of another dadgum winter, muchachos.

Next Time: NexRemote Again…

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