Sunday, December 18, 2016
Issue #522: Almost There, Almost There…
After last week’s slightly controversial topic, we’re back on calmer ground with the next to the last installment of my Messier series. The end of these articles will not be the end of my writing on the Ms, however. I have another series planned and hope to start it in the new year. Why? After many years of ignoring Chuck’s list in my quest for the dimmest of the dim, I find I have been drawn back to these beautiful—well, with a couple of ringers—deep sky objects.
This week we are heavy on galaxies. In fact, all but one of this week's crew are galaxies, the exception being a single open cluster. That cluster is also the only one of this bunch that is readily visible now. Take heart, though; before you know it the Lion and the Virgin will be back and with them these wonderful (and sometimes challenging) island universes. Prepare now to take on the Virgo challenge, touring all of the maiden’s and Coma's M-galaxies when spring comes again to the Northern Hemisphere.
Messier 99, the Pinwheel Nebula (galaxy), is, in pictures anyway, a beautiful near face-on Sc spiral galaxy located on the western end of the great Virgo cloud. A look at its specs, magnitude 9.87 and a size of 5’44” x 4’22” don’t make M99 sound overly difficult. That’s what I thought reading them when I was a youngun before trying to run this beast down from my parents’ suburban backyard. I mean, my 4-inch Palomar Junior reflector would easily show a 10th magnitude star, so why shouldn’t it show this brighter than 10 galaxy even more easily?
Reality was a bit different as I found as soon as I began hunting the Pinwheel. There are plenty of galaxies in this area, and I thought I'd found M99 a time or two, but no. The star field around the galaxy is fairly distinctive, and the tools I had at hand, Becvar’s Skalnate Pleso atlas (I knew better than to try to navigate Virgo-Coma with Norton’s) and the wonderful “A Messier Album” column in Sky & Telescope said “nope.” In fact, I don’t think I saw M99 with the Pal Junior until the 1980s, though I had of course seen it with other scopes by then.
The problem for me was that while this galaxy is somewhat bright, it’s also somewhat large, and, worse, it is a face-on spiral, the most challenging species of galaxy for backyard observers. Couple that with small aperture and primitive 1960s eyepieces (war surplus optics), and M99 was way difficult. Luckily for you, today you're likely armed with more knowledge, better finding tools, good oculars, and larger aperture than I had way back when. It is now more than possible to find M99 from the back forty on a good night, even without goto.
As a young observer, it was a point of honor with me to learn to navigate the Realm of the Galaxies. I remember that being challenging (in a good way) but also frustrating. It still is both those things today, though we have deeper print atlases to help, atlases like Uranometria 2000 (a good choice for Virgo) and far, far deeper computer atlases like TheSky and SkyTools. Still, if you are more interested in seeing that hunting, at least in this crowded area, you’ll be much happier with go-to or digital setting circles.
If you want to or have to do things the old-fashioned way, this is one that is not too terribly difficult. You’ll find the Pinwheel, which is not actually in Virgo but over the border in Coma Berenices, lurking a mere 49’ southeast of a decently bright guide star, magnitude 5.05 6 Comae. In the field of the target object is a distinctive magnitude 7 range star, the brightest in the immediate area.
Forget the sweeping arms that give this galaxy its name. What you will see in the backyard, even with some fairly large aperture scopes, will be a slightly elongated lint-ball with a brighter center and, on especially good evenings, a tiny core. From a dark site, however, a 10 - 12-inch telescope will begin to show hints of spiral structure in the haze surrounding the galaxy’s small nucleus.
You wanna know how hard M100 is to observe? It’s like M99, only worse (for the backyard bound). Yes, at magnitude 9.35, it is slightly brighter than M99, but at a size of 7’24” x 6’18” it is considerably larger, which is a bad thing, especially with face-on spirals whose light is badly spread out by their orientation to begin with. Still, it’s on our list, so let’s go get this rascal, which is sometimes nicknamed “the Blow Dryer Galaxy” (don’t ask me why).
The easiest way to find M100 without electronic aid is by finding M99 first. Then, move 1-degree 44’ to the northeast and you should be on the proper field. There are no bright stars in the area, so move slowly and carefully and use a detailed computer charting program to help you.
Actually, there is another way to find this one or any other deep sky object: with analog setting circles. Yes, those old fashioned “dials” can work. IF. The biggest problem with analog circles on amateur mounts is their size, or lack thereof. Those on many GEM mounts are too little to be anything more than useless decoration. Those on the average SCT are better. Yes, the declination circles are still small, but the RA circles are large enough to work well. Both also have verniers (instructions for using them are here).
The main requirement for using setting circles successfully is that you be well polar aligned. The closer you are to the pole, the more accurate they will be. Oh, and you will have to calibrate the RA circle every time you use the scope (with the drive turned off, the RA circle, like a clock, loses “time”). Best bet is to go to a star as close to your object as possible and set the circle to the star’s correct RA. The declination circle on SCTs is set at the factory and shouldn’t have to be messed with often, but if you need to calibrate in declination do just like you did for RA.
When everything is ready, what kind of accuracy can you expect? I used the analog circles on my Celestron Ultima 8 SCT, Celeste, to navigate Virgo successfully one year at the (old spring) Peach State Star Gaze. No, everything I went for was not always in the field even at low power, but most of the time objects were close, and I only had to do a little hunting around. At the very least, "manual" circles will get you in the neighborhood, and a 50mm finder will allow you to quickly refine your aim. You can also use analog circles on a Dob, and perhaps we’ll talk about that next installment. Can analog circles be good as digital setting circles? No, not even close, but better than just using a finder/Telrad in bright skies? Yes.
Anyhow, when you are on M100, what you will see from the average suburban backyard is, unfortunately, “Not much, amigo.” Under good conditions you will see a large round fuzz spot that gets brighter toward its middle. You may also be able to make out its star-like nucleus. That is normally all. At the dark site? With larger apertures, some details, dust lanes and mottling, are apparent, but don’t expect slap-you-in-the-face spiral structure. You may also glimpse a small 14th magnitude companion galaxy, NGC 4322, 5.0’ to the southwest.
You thought M99 and M100 were tough? Hoo-boy! M101, the Catherine Wheel Galaxy, is, with M74, the toughest of the tough in the Messiers. Why? Like the previous two, it’s a face-on Sc spiral. But it is worse. Way worse. The reason is that it’s also huge, 28’48” x 26’54”. Yes, M101’s visual magnitude is 7.8, but, remember, that means it is the same brightness as a magnitude 7.8 star thrown out of focus till it occupies nearly half a degree of field. Not only is its light badly spread out, it is difficult to frame it so as to provide some contrast. You want some dark sky around this big galaxy to furnish that contrast, but you’ll have to use a low power eyepiece to do it. In the suburbs, the sky background is bright at low power, so you get no contrast gain.
The good part? Finding this galaxy’s location is easy. It forms a near equilateral triangle with the two end stars of the Big Dipper, Alkaid and Mizar. Insert a medium power eyepiece that gives somewhat over half a degree of true field in your telescope—before the advent of 100-degree AFOV eyepieces, I liked 12 and 16mm 82 degree oculars depending on the scope I was using—and start staring.
I don’t want to give you the idea that this galaxy is impossible from the suburbs; it is not. When I was writing The Urban Astronomer’s Guide I saw it frequently with my C11 (albeit sometimes with difficulty) or, on superior nights, with the 8-inch f/5 Newtonian I was using for some of the book’s observing. It wasn’t easy, though, not even with the C11. And I certainly could not see details:
M101 is one of the real challenges from the suburbs, and I didn't expect much on this relatively poor night. Try as I might, I couldn't see any hint of its outer nebulosity much less the spiral arms. After examining the field for a while with the 12mm Nagler at 220x, I did catch sight of with appeared to be its central area, a faint spot about 10' across, but this was not easy in the C11.
At a dark site, of course, it is a much different story. I’ve seen the galaxy easily with 10 x 50 binoculars from the very dark Spruce Knob Mountain in West Virginia, and reveled in its spiral arms with the C8 at f/6.3 on good evenings from less superior locations, like French Camp, Mississippi, home of the Mid South Star Gaze. On the very best nights, an LPR filter reveals the arms are peppered with HII regions, M101’s nebulae.
Take a break, Jake. There is no M102. NGC 5866 has often been suggested as M102, but it is clear to me that 102 was nothing more than a re-observation of 101. If you can’t bring yourself to accept that, by all means take a gander at NGC 5866; it’s not a bad object. I’ll wait right here.
Let’s take another break, from dim and difficult galaxies at least. M103 in Cassiopeia is a bright (magnitude 7.3) and small (6.0’) open star cluster. It’s a beauty, though it would be even more beautiful if it weren’t set in such a rich star field. As it is, it is sometimes slightly difficult to distinguish the actual cluster from the background in wide-field telescopes from dark locations.
There is nothing to finding 103. It lies 1-degree northeast of bright Ruchbah, a magnitude 2.65 sun that is one of the stars of Cassiopeia’s “W.” When you’re on the proper spot, have a look through your finder (scope). The cluster should be visible as a short line of three or four brighter stars.
When you are on Messier 103 with the main scope with a medium power eyepiece, especially a medium power wide-field eyepiece (such oculars are surprisingly inexpensive now), you are gonna like what you see, yes indeed. My impression is that this looks much like Cygnus’ M39, a small triangle of brighter stars with plenty of dimmer ones both within and just outside that triangle. The view is made even prettier by the presence of a red-orange central star at the heart of the cluster. And the whole thing is set in that crowded star field, which really looks super from my club dark site.
Gosh-a-mighty, how I loved the Hale Reflector photographs of M104, the Sombrero Galaxy, when I was a kid. This is one of the relatively few objects that didn’t disappoint me too much when I first saw it with my 4-inch. Oh, the view through my 1-inch Kellner eyepiece couldn’t compare to 200-inch plates, but, still, the basic features were there and I was thrilled to see the renowned Sombrero with my own eyes.
How to locate? This magnitude 8.0, 8’42” x 3’30” near-edge-on lies in Virgo, but I always find it easier to star hop to from Corvus. Begin at magnitude 2.90 Algorab. About 2-degrees 45’ north of the star you will notice (in the finder scope) a Y-shaped asterism of magnitude 6.0 range stars. Trace this asterism as shown in the picture, and you will find M104 just 25’ to the east of the last Y star.
When there, your first impression may be, as was mine as a 12-year-old, that the Sombrero is smaller than you thought it would be. Pump up the power to at least 150x, though, and you will begin to see those legendary details, the “hat brim” and the “crown,” at least. A 6-inch refractor or an 8-inch reflector will show the famous equatorial dust lane readily on a good night. Yes, it is doable with smaller apertures, but you’ll have to find a magnification that makes the galaxy big enough so you can see much of anything, but which also doesn’t make it too dim.
We’ll end this installment with another easy, pretty view. While Leo’s M105 is relatively dim as far as its magnitude value, 9.79, goes, it is a medium sized (5’24”), almost round elliptical with a bright center that makes it pretty easy, even in a 4-inch. Normally, E galaxies aren’t that attractive, but this one has a couple of aces up its sleeve, two companion galaxies, magnitude 10.0, 3’49” NGC 3384 7’19” to the northeast, and magnitude 12.83, 2’49” NGC 3389 9’29” to the southeast. The three together make for a superb view.
Locating M105 by manual means can be hard or easy depending on how dark your skies are and how high the lion is in them. The best way to get to the group is to star-hop 1-degree 38’ south from Kappa Leonis. While that star is often invisible or nearly so in the average suburban yard thanks to its magnitude of 5.45, it will how up readily in a finder scope.
After you get done admiring Messier 105 itself, see if you can pick out the two companions that form a triangle with the Messier galaxy. The dimmest member, NGC 3389’s, 12.83 magnitude figure sounds daunting, but I could regularly see it from the heavily light polluted backyard of Chaos Manor South with my 12-inch Dobsonian, Old Betsy, thanks to its small size. Not only do you get a pretty triangle of galaxies here, M95 and M96, that pair of galaxies we visited just a while ago, is only a degree to the southwest if you want to go on a side trip.
One more and we will be done with the Ms, but that won’t come for a while yet. Christmas, if nothing else, is going to intervene. As is usual, the next blog will arrive on Christmas Eve rather than Sunday, and will likely be shorter and perhaps more sentimental than usual.
Nota Bene: I’ve received word that for a variety of reasons the author of Deepsky Astronomy Software, Steve Tuma, is discontinuing sales and support of his program. While there are other more modern planning programs available today, DAS was one of the first and still has some great features. Features like copious log notes for many objects from accomplished observers—something I find often comes in handy. If I were you, I’d contact Steve and see if you can still get a copy...
Hello Rod, Very nice write up as usual. Rod will or can you some write up on video astronomy using your mallincams ? maybe you all ready did. I might have missed them . thanks will w
I've done quite a few articles on the Mallincam, including one for Sky & Telescope. There are quite a few blog articles, too...just google "Uncle Rod Mallincam." Here's one I did for ATT.
The Deepsky Astronomy website is gone (http://www.deepsky2000.com). I get a godaddy ad that it's for sale. So, I guess there's no easy way to contact Mr. Tuma.
Steve writes: "I still have 6 sets of dvds left. If anyone wants a set just email me to my new email email@example.com and i will work something out with you."Post a Comment