Sunday, December 07, 2008

 

My Favortie Fuzzies: M101

I love the Messiers. No matter how often I go back to M42 or M13 or M17 or any of the rest, I never get tired of ‘em; I almost always see something new. Not that I don’t have my pets amongst the Ms, those objects that, while not necessarily the brightest or the “best,” have special significance for me. I’d like to share some of those with y’all as we wait for the barreling cold fronts of winter to roar through and bring dark (if not steady) skies.

First up is the great galaxy M101, The Pinwheel. Yeah, I know she ain’t exactly well placed for observing at the moment, but the Big Bear and M101 will be back in early-mid evening skies before you know it, and this blog entry is designed to both whet your appetite for this spiral monster and to maybe help you develop a strategy for attacking the thing. Most times, you see, M101 is one of the real hard ones as Messiers go. A pest. A hairline reducer.

As I found out in short order when I first started running The M List in 1965. Yep, my relationship with this Grand Design spiral goes back to when I was a sprout. You know, knee-high to a grasshopper—or a Palomar Junior. My first glimpse of this one was probably in a little book called Universe from a long-gone publisher called Science Service who pushed kid’s science books from the pages Boy's Life magazine. They were surprisingly good little books, but that is a story for another time.

The story for this time is merely the glorious black and white picture of M101 that graced Universe’s pages. The image, likely taken with the 200-inch Hale at Mount Palomar, just turned the 11-year-old Rodster on. Those lovely spiral arms, sweeping on forever; that was what I wanted to see. It’s probably not a stretch to say pictures of face-on galaxies like M101 and M74 are what really got me going in amateur astronomy. Even today I cannot adequately explain the attraction; there was just something about those pinwheeling arms that lit a fire in me.

So, naturally, when I finally did get my telescope, M101 was one of the first DSOs I went hunting for after I tracked down M31 (looked much worse in my Tasco than I hoped it would) and M42 (looked much better in my Tasco than I feared it would). Finding 101's approximate spot on the sky was not difficult; it forms a near equilateral triangle with two of the Dipper/Plough’s famous stars, Alcor and Alkaid. This spiral’s specs, which I probably gleaned from Patrick Moore's The Amateur Astronomer didn’t sound that off-putting, either: “M101, NGC 5457, Magnitude 8.3, 28.8’ x 26.9.” That meant this one was, I thought, BIG AND BRIGHT. Yep, soon as The Bear lifted herself away from the horizon I’d be in spiral arm nirvana. Not.

If you’re anything other than the rankest novice, you’re probably getting a good chuckle out of this. Yep, Little Rod bravely carried his three-inch Tasco into his suburban backyard, lined it up on the approximate position of the galaxy via the scope’s peep sight, and looked and looked and looked. And saw—absolutely nothing. Not a trace, not a smidge of a spiral arm did I see. In fact, I didn’t see nuttin’ at all. Nary a bit of nebulosity did I discern beyond some faint smudges that I decided were in my mind rather than my eye.

Oh, I didn’t give up—for a while. I kept coming back to the area, but with zero results. I eventually did throw in the towel for a while, putting my failure down to my punk little scope or deficiencies in my suburban sky. Which was part of it. 3-inches of aperture is a little small for this beast, and my subdivision sky, though probably better than what most of us suffer through today, was not exactly dark. Those were not the real problems, though. Little Rod’s FAIL came because he didn’t know what he was looking for, nor did he know how to look for it.

What should I have been looking for? Seeing as the stated magnitude value for M101 was 8.3, I expected it to be dimmer than M42, sure, but pretty easy nevertheless, and given its size of .5 degree, I shouldn’t have been able to miss it. The problem was I was too dumb to put 2 and 2 together. Take a magnitude of 8.3, spread it out over near half a degree, and that makes the surface brightness of this one about magnitude 15 or worse. The exact same thing as centering a magnitude 8.3 star and defocusing it until it fills the field. Dim. Not impossible, no, but I shoulda been looking for something just barely on the threshold of detection. And you have to know just how to approach such a thang.

The secret being "don’t spread out that magnitude 8.3 light so much." I’ve seen this beast easily in 10x50mm binoculars. At 10 power, the light stays tight and close to that 8.3 value. But there’s a gotcha. If you run at very low magnification, any background skyglow is prominent too—it’s not spread out either. This dim ghost of a galaxy is so close to the brightness of the sky from the typical backyard that it melts right into the gray eyepiece field. To fight that you will need dark skies. Get out in the backwoods and the galaxy pops right out. I’ve also found that dry sky is almost as important as dark sky. If there is a lot of moisture in the air, any light pollution will be exaggerated; a small light dome will grow to frightening proportions.

Can you conquer The Pinwheel with aperture?  Larger aperture usually comes with a smaller field of view. If M101 fills the field, you will not be able to tell where she begins and ends. You need to leave enough sky around the galaxy to provide some contrast. Which is made fairly easy by today’s ultrawidefield eyepieces. You can pour on enough power to spread out the background light pollution enough to make M101 pop out, but still have enough true field of view to provide some dark sky around this devil.

When I was writing my urban observing book, The Urban Astronomer’s Guide, I found a 12 – 16mm 82 degree AFOV ocular did the trick with my C11 at f/6.3. I could see M101 almost anytime it was near culmination. By “see,” of course, I don’t mean I could see spiral structure; I just mean I could make out the galaxy’s nucleus and a tetch of haze that represented its outer regions. Getting a look at the arms demands dark skies.

Oh, I suppose I oughta mention for those of y’all getting into the astro picture-taking side of amateur life that M101 is trivial to image, even under compromised skies. The above humble snapshot of mine was taken from a site a mere 60-miles or so from the light pollution hell that is Atlanta, Georgia. The nice boys 'n girls of the Flint River Astronomical Society had invited me up to their Georgia Sky View star party, and I’d brought along my Meade DSI CCD camera and CG5-mounted C8 for some casual deep sky snapshooting. While seeing wasn’t great, and the sky was indeed a bit bright, that didn’t stop me from capturing an at least recognizable Pinwheel with 30 or so unguided 30-second exposures. Not bad for a CCD beginner, I reckon, but really more a testament to the ease with which this galaxy can be imaged as opposed to the difficulty of seeing it—at least its details, anyway—visually.

I learned to look for and at M101 up in the dark foothills of the Ozark Mountains back in the 1970s. Velvet black skies and relatively dry air meant that M101 fell right in line with the rest of the Ms: “Not challenging, showpieces.” Strange as it may seem, though, my best look at this galaxy did not take place during one of me and my buddies’ storied dark-sky rampages in hillbilly land. It was not, in fact, until twenty years later that I got what I guess is my to-now definitive look at this face-on marvel of an island universe.

Mississippi’s Mid South Star Gaze takes place each spring at a site near the wee town of French Camp, Mississippi in the northern part of the state. Back in the mid-90s, before Miss Dorothy and I attained full workaholic-hood, we made the pilgrimage to French Camp a couple of times. We were impressed both with the facilities and with the darkness of the site’s skies. If not always with the weather. Being located just east of Tornado Alley, that part of the state is in the path of some fierce storms in the spring. As we found out.

Mid South, which is sponsored by a local (fundamentalist) religious school, French Camp Academy, in those days was run by an extrodinary amateur astronomer and astronomy educator, Jim Hill, and was sited on a hilltop he had turned into an amazing astronomy education facility. In addition to numerous large and varied telescopes and observatories to house them, this pasture-ringed hill boasted an honest-to-god planetarium dome, lavish warm rooms equipped with Internet connected computers, and more. Things have changed in recent times—read the above linked post if you are interested to know how—but back then MSSG was an excellent event.

Miss D. and I were just enjoying the heck out of the site and its marvelous skies one deep spring night. After messing around in Virgo for a while, I decided that with that grumpy ol’ bear at culmination it would be a perfect time to seek out her marvels. M108, The Owl, and, of course, M101. I wasn’t toting a big gun, just my beloved Ultima 8 SCT, so I was not quite sure what I would see. A look through the finder, once I’d moved the C8 to point in M101’s general direction, though, tipped me off that what I was gonna see was gonna be memorable; the galaxy stood out starkly as a round glow in the 9x50.

I centered said round glow in the field of one of Celestron’s late, great 26mm “Silver Top” Plössls, and then pulled out my then-current pride and joy, a 12mm TeleVue Nagler Type II. Oh. My. God.  The darkness of the site combined with the excellent contrast of the Nagler meant tracing spiral structure was as easy as falling off a log. I kept switching back and forth between the Nag and the Silver Top and honestly couldn’t decide which I liked better. Oh, it was good; the galaxy’s nucleus was tiny and burning bright and, especially with averted vision, the arms just bloomed to life. Then I had a wild idea. I’d just purchased a Lumincon OIII from the star party’s vendor, Rex’s AstroStuff. What might that filter do to the galaxy?

Don’t look at me like that, y’all. By 1995, I’d used Light Pollution Reduction filters more than a little. I knew they dim stars and anything made outa stars. Like galaxies. Like M101. What I was after was M101’s HII regions. Wut? “HII” regions are nebulae. Under good conditions; especially in images, face-on galaxies are peppered with their equivalents of M42 and Eta Carina. Onto the 26 went the OIII. Suddenly M101 looked like she had a bad case of the measles. I was just hopping up and down at the sight—literally—and was about to start grabbing nearby observers and insisting they have a look. But then Jim Hill walked onto the field and intoned: “Folks, we are under a tornado WARNING.”

Yep, that’s what the man said. “Tornado.” And not “watch,” “warning.” What the—? How could that be? I was peering out 25 million light years into intergalactic space to a galaxy glowing like a danged neon bulb. Then I turned and faced west. Despite the darkness of the skies, I could detect a darker line right along the horizon. I knew from my Arkansas days that that meant bad stuff was on its way.

In short order, I and the other folks on the field were not just covering our scopes; we were disassembling them and loading them into our vehicles. By the time Dorothy and I made it back to the relative safety of our bed and breakfast in town, the bottom really did fall out. Not just torrential rain, but high winds (if a tornado didn’t pass through, its sister did) and some of the most intensive and intimidating thunder and lightning I have ever heard.

We spent the balance of the evening huddled with our Possum Swamp Astronomical Society buddies (we’d convoyed up), talking over old times and various misadventures while sipping (those brave enough) potations poured out of Unk’s omnipresent bottle of Rebel Yell. It was nice and all to relive the Good Old Days—like the night Bubba set one of his tripod legs in a fire-ant mount and wondered, for a while, why he couldn’t level the dang thing. What I was thinking about mostly, though, was what I had seen. And when we finally called it a night, the persistent vision of that giant night-bird of a galaxy led me into my dreams.

Silicon Sky Redux: What Got Left Out

Yeah, when I was running through my fave planetariums and planners a couple of blogs back, I knew dadgum good and well that I would, as I warned y’all, leave some out. I still can’t believe what I left out, though: three of the best astronomy apps on the planet. My thanks to the good folks who pointed out my dumb omissions, and my apologies to the creators of these wonderful programs.

SkyMap Pro

Is Chris Marriott’s SkyMap Pro (now in Version 11) a planetarium or is it a planner? OK, it’s a planetarium, but one with some fairly robust planning features, at least compared to its brethren. No, it ain’t no SkyTools, but it is still capable of putting together observing lists for you without much fuss. Not only can you tell the program “Gimme all the Ursa Major galaxies brighter than magnitude 11 and put ‘em in the list,” you can click on objects on the program’s virtual sky and, if you want, include ‘em in the list, too. The program even ships with some ready made observing lists for your use—Herschel 400, Messier, etc. SkyMap has a very competent logging system, too, thank you.

But there’s no denying the main draw here is the planetarium, and it’s an outstanding one. While it ain’t crazy-heavy on objects (about 200,000 DSOs and 15 million stars), there’s ever’thing here that you or me is likely to wanna take a gander at. And SkyMap presents these objects in the context of beautiful and responsive charts. It does a great job of printing these charts, as well, if you don’t feel like toting a blankety-blank laptop into the field. You do want to carry the laptop out? Since SkyMap now supports ASCOM, it can talk to near-‘bout any telescope under the Sun. What more could you want? You tell me, but chances are SkyMap can do it, since this is just the teeny-tiniest sample of this heavy-weight’s features.

NexStar Observer’s List

The only excuse I can offer for not including Michael Swanson’s NexStar Observer’s List (NSOL) with the other planners is that it’s aimed at a narrower audience than the rest of ‘em, users of Celestron’s NexStar series of go-to scopes. That really ain’t no excuse, though. This planner is more than good enough to make it worthy of a place among its brethren. It ain’t fancy, no; it don’t have umpteen bazillion objects, but it does have what most of us are after, the Messier and the NGC, and a few others things besides like the Abell galaxy clusters. The program’s list generation tools are fairly simple: you open a catalog, sort on various fields, search by names or IDs, and send the objects of your choice to your list. This simplicity does have its strengths. I sometimes forget what the hail I’m supposed to do with SkyTools or AstroPlanner, but I never forget how to work NSOL.

What else is NSOL good for? Since this one is designed specifically for Celestron scopes, it offers some features of special interest to the Orange Gang. Like a utility to help you pick the best alignment stars and a simple star chart to help identify ‘em. There’s sufficient data presented for each object, and even a (very) basic star chart to show you where the heck that faint fuzzy is located. The “Hyper Hand Control” is an onscreen “replacement” for the HC that allows NS mavens to easily access, sort, and go-to any of the 47,000 objects in the program’s database. Finally, being specifically developed for use with NexStars, NSOL works very well indeed with that real replacement for the HC, NexRemote. I love NSOL, use it frequently, and can’t believe Mr. Mike still gives it away for free.

StarCalc

Thought you knew about all the good freeware planetariums, didja? You don’t. Not if you haven’t tried A. E. Zavalishin’s StarCalc Version 5.72, you don’t. What’s it like? It’s a planetarium with a very clean, well-laid-out user interface, one that reminds me a lot of SkyMap Pro’s sky-window—and that’s a good thing. What else? In addition to being iron-clad solid as far as behavior on my ‘puters, StarCalc offers one very impressive thing: speed. It’s remarkably efficient in its calculations, and is easily capable of slamming a virtual sky onto the display of an older PC in just a couple of seconds. Data? Not bad. It ain’t no Megastar, but it does have the Tycho Star Catalog, a “plugin” that allows the use of the Hubble Guide Star Catalog, and the NGC. I would also guess that StarCalc’s plugin system, which makes it easy to use external catalogs, should mean that there’re plenty of user provided catalogs out there—though I haven’t looked. Finally, the program has a print function that produces very nice-looking hard copy.

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