Issue #481: The List Part I

Birders, bird watchers, have what they call a “life list.”  That is a list of the birds they’ve seen/hope to see. We amateur astronomers have something similar, the Messier list. That’s the catalog of 110 (more or less) deep sky objects, galaxies, nebulae, and clusters, compiled by 18^th Century comet hound Charles Messier from his observations of fuzzy things in his telescope’s eyepiece that he thought might masquerade as comets.

Warning comet hunters off these puzzling non-comet things was Chuck's initial goal in composing his list, anyway, but it contains some DSOs that you wouldn’t think could be mistaken for comets under any circumstances, things like M45, the Pleiades, the famous Seven Sisters. And in addition to his observations, the M-list contains some objects known historically and others found by his friends and contemporaries. Observers who came after Messier added a few more and modified a few, and what we have today is a catalog of bright and spectacular objects every amateur wants to see and should see.

I’ve written on quite a few of the Messiers here, usually in my “My Favorite Fuzzies” series, but I thought it was time to take on the whole list, to give my impression of all these objects and my advice on viewing all of them successfully. While this is sorta newbie-oriented I suppose, I know I for one have never tired of both observing and reading about these wonders. I intend to cover the entire catalog in a reasonably short time, though we are starting off in modest fashion. Here’s the first (small) batch.

M1 (The Crab)

M1 sketch with 10-inch Zelda...

When I was a wee sprout just learning to use a telescope and preparing to embark on the Messiers, I supposed the first one, the Crab Nebula, must be special. Especially bright, maybe, or at least especially good. Otherwise why would it be first on the list? You can imagine my dismay when I finally ran it down with my 4.25-inch Palomar Junior reflector from my suburban backyard. It was not overly easy for novice me to find even though there’s a good signpost to it—it’s about a degree northwest of the bright star Eta Tauri. When I had it in the eyepiece, though, and it took a while for me to convince myself I did, I was not a happy camper. M1 sure didn’t look anything like a crab, and certainly nothing like the Mount Palomar image of it I’d long admired. In fact, it was barely there at all. It was a small, smoky-gray oval of light just on the edge of perception.

Of course, as the years went on I got better telescopes and better views of Old Crabby, but this supernova remnant, what's left of a star that blew its top in 1054, is not as easy an object to see as you'd think given its Messier status. Its specs don’t look too punishing, magnitude 8.4 and 8.0’ across, but believe me in a 4-inch telescope in the backyard it can be a very dim little oval. In a six inch it is better, perhaps, but still really just a slightly brighter dim oval.

In my 10-inch Dobsonian, Zelda, however, even in the backyard, things begin to change. On a good night with M1 riding high, it begins to look more like a lightning bolt or an “S” shape than just an oval. A UHC type light pollution reduction filter helps make the lightning bolt shape more obvious, but the difference with and without a filter is not overwhelming. On the best nights, I can make out that the nebula's edges are irregular and that there are darker and brighter patches scattered across its surface.

But how about those tendrils of gas, the feature that made the Earl of Rosse think M1 somewhat resembled a crab in his big scope? Forget them without dark skies and/or plenty of aperture. To have a prayer of seeing them, you will need an OIII filter. Unfortunately, that tends to dim the “body” of the crab, and you still don't get an overall effect that looks anything like the photos of this object. Under good conditions from a suburban-country transition site, I have been able to see the brightest tendril with a 24-inch Dobsonian. I was also able to see portions of it with my old 12.5-inch Dobsonian, Old Betsy, but only from a somewhat darker location. So, no, not easy. These days I tend to give the Crab quick looks from my backyard, and reserve serious observing for star party nights. Or I use my Mallincam Xtreme on it, which gives a better view than any amateur scope will visually.

M2

M2 with a 5-inch MCT...

If M1 is subtle in telescopes big and small, M2 is spectacular in them. Even in a 4-inch, this big magnitude 6.6, 16’ across globular star cluster can show considerable resolution under good conditions. On the other hand, locating it can be somewhat of a pain for novice observers without goto mounts thanks to its location amid the stars of the relatively dim autumn constellation Aquarius. The best way to track down this glob is to move 4-degrees 45’ almost due north of reasonably prominent Beta Aquarii. A medium-low power eyepiece should reveal M2 without much trouble, since it is not too far down in the south, being located almost smack on the Celestial Equator.

If you are using a 4-inch or even a 6-inch scope, this star cluster might not be overly impressive at first from your backyard. Not at low power, anyway. Increase magnification, starting at about 150x, and you will eventually hit on a combination of power and field that shows the object’s potential.

In my backyard, 250x  does a good job with the 10-inch Dob, but you don't need that much aperture for a good look at this one from only slightly better skies. Out at my club's (semi) dark site, M2 looks considerably better in my 5-inch refractor at 200x than it does back home with the 10 at 250 or even 300x. What’s it like? Intense core and string after string of tiny stars emanating from that. One of the most memorable things about it, however, is its (to me) blue tint.

M3

If M13 is the king of the summer globulars in the opinion of some folks, M3 rules the spring objects. M53 over in neighboring Coma Berenices is not really much of a spectacle for backyard-bound telescopes unless you can pour on a lot of aperture. And if you are able to do that, M3 still wins the globular star cluster race handily.

What will you find in your eyepiece when you get to Messier 3? First you have to get to it, to the correct field, if you are going “manual,” which I’ve always had trouble doing with M3 for some reason. In fact, I used to refer to this object as one of my “finding demons.” Even today, if I try to approach it the way I used to, making a big equilateral triangle out of Arcturus, Rho Bootes, and M3 I am usually stymied for quite a while. You’d think it would be impossible to miss such a relatively big and brilliant thing (magnitude 6.3, 18.0' across) even in the backyard. And yet I can do just that. I’ll set and reset the scope on what I think is the proper area (you can’t depend on it being obvious in a finder from the backyard), all the while saying bad words and seeing no globular star cluster at all.

A better plan? A more reliable way to land on M3 quickly is to extend a line for about 6 degrees 45-minutes east and just slightly north of Beta Comae. One other huge tip? If your backyard sky is badly compromised, forget a Telrad or Rigel Quick Finder for anything but roughly positioning your telescope. In the average suburban back-forty, magnitude 4.26 Beta may be invisible or nearly so naked eye. It will show up easily in a 50mm finder, though.

M3 from years ago. One of my first CCD images...

What I use to good effect for finding with my non-goto 10-inch Dobsonian, Zelda, is the combination of a Quick Finder and a 50mm right-angle-correct-image optical finder. The QF makes it easy to get in the general vicinity of a target (I can have a hard time doing that with any finder that uses a 90-degree diagonal), and I can then look in the 50mm finder and immediately pick-out the stars shown on my atlas or on SkySafari’s display. Once I get in the proper area, I do love the comfort of the RACI finder’s diagonal.

So you are finally on M3, have bumped the magnification up to 150x or so, and are taking a good long look. What will you see? Here’s what turned up in my old NexStar 11 GPS one long ago night at the Georgia Sky View Star Party: 

In the TeleVue 22mm Panoptic at 127x, M3 is about as perfect as it ever gets. Outlying stars extend across the whole eyepiece field. All the stars are exceedingly tiny, and it appears resolved to the core. The core itself looks rather strange tonight, appearing as almost triangular. 

Sure, the skies at the GSV were darker than my backyard—if hardly perfect, the site being only 60-miles from Atlanta—but I can see the cluster almost as well on a good evening from home using the 10-inch Zhumell.

M4 (Cat’s Eye)

This big globular in Scorpius has one thing going for it and two things against it. In its favor, it is bright. Magnitude 5.9 puts it just behind M13, which shines at magnitude 5.8. Not so fast, though. M4 is also big, 36’ across, and low at a declination of -26-degrees 31’. Even from my Gulf Coast digs it is fairly far down in the southern sky at culmination. It’s also loose. This is no M13. While it’s easier to resolve stars in M4 than it is in M13 with a 4-incher, the overall impression this cluster gives is "loose." Out in the dark, you get dimmer fill-in stars that make it look better, but the general impression is “weak,” and this wouldn’t be a very good one if it weren’t for its cat’s eye aspect, which it showed off to me at the same star party where I did M3:

M4 is perfectly framed at 103x. Resolved to the core, it shows off its loose structure well. There’s a somewhat bizarre double line of stars across its center that looks a little like the iris of a cat’s eye, and is the reason for its nickname, the Cat's Eye cluster.  

M5

M5 in another very early CCD image attempt...

I don’t believe Messier 5 has a nickname. Never heard one used for it, anyway. If it were to be given one, though, that ought to be “The King.” M5, not M13, is the best glob for Northern Hemisphere observers in my opinion. I’ve thought that for a long time. Even said so to the outrage of a few folks in an article I did long ago for the old Amateur Astronomy Magazine when it was in the hands of its creator, Tom Clark.

Why do I think this? M5 is slightly brighter than M13 at magnitude 5.7, but it is also slightly larger at 23’ in diameter. Doesn’t matter. To me it just looks much better in any telescope. For one thing, despite being given the same Shapley-Sawyer concentration class as M13, V (intermediate rich concentration), M5 always seems a bit easier for me to resolve with smaller instruments than its rival.

Anyhow, I know it looked just wonderful on the same evening I logged M5 and M3 from the heart of Georgia:

This really is the most beautiful globular in the northern sky in my opinion. Displays an obvious overall blue hue. The shape of the cluster is defined by arcing lines of stars. Core resolved, extends across the field of the TeleVue 22mm Panoptic at 127x.

So what’s next for me? This was not an amateur astronomy weekend, though the event I attended did feature a couple of talks about our sport. Dorothy and I were at our area’s biggest nerd-fest, Pensacon 2016, this past Saturday. This comics-SF-anime-gaming-Trek-scifi movie con will be the subject of the next installment here, and is why this article was a mite short. After that I will be back to the telescope game, however, and if you liked this initial batch of Ms, let me know, and I will continue the series.