Sunday, June 26, 2016
Getting a Black Eye
But in a good way, as in gazing at the wondrous Blackeye Galaxy, M64. Yep, here is another Messier installment that features a showpiece, if one that’s maybe not quite as spectacular as last week’s M57. Actually, we’ve got not just one showpiece this morning but—count ‘em—three. There are two other goodies in this group that, while maybe not as pretty individually as M64, pack a real wallop when seen together: M65 and M66.
‘Course, to see these beauties you gotta have something to look at ‘em with. I’m not talking about your telescope. We’ve covered that ground a couple of times already. What I am talking about is something that is often claimed to be at least as important as the telescope, eyepieces.
What do I like for Messiers ocular-wise? Those who know me know I am addicted to ultra-wide apparent field eyepieces: 68-degrees, 82-degrees, 100-degrees, more. I just love the sensation of looking through a gigantic spaceship porthole. And there are practical reasons to embrace ultra-wide fields. More apparent field brings more true field with it. If you are using an un-driven Dobsonian, a larger true field means less frequent nudge-nudge-nudging to track objects.
And especially less nudge-nudge-nudging at the medium powers that are so useful in the backyard. A 12 - 14mm range eyepiece with an 82-degree apparent field gives you plenty of space, but enough magnification when used in the average telescope to spread out that yucky background sky glow and increase contrast a bit.
Unfortunately, heretofore ultra-wide fields came at a price, a price in money that was too high to allow some of us to experience 82-degrees or 100-degrees of heaven. That’s changed in the last few years with the introduction of reasonably priced imported ultra-wide angle eyepieces (actually, even top of the line oculars are imported today).
How good are these budget priced (well sorta) alternatives? The 82s have been very good for a long while. Some years ago, I tested the Uwans from William Optics and found them fully competitive with the high priced spread in almost every way. Since then, Mainland Chinese 82s have become something of a drug on the market, with very good ones from folks like Meade and Explore Scientific going for as little as 130 bucks a pop. How good are they? Very good. Usually at least as good as and sometimes better than the Uwans of yore.
What if you want MORE though? What if you want 100-freaking-degrees of AFOV? I wanted that very thing some years ago, a 100 in the 16mm focal length neighborhood. But I couldn’t afford the Cadillac, which was well over 700 dollars at the time. What my modest budget would allow was one of the first 100-degree eyepieces to come to these shores from Mainland China. These were sold wearing a variety of badges including Zhumell, Orion, and TMB. I ordered the Zhumell, not quite sure what I would get, but being pretty convinced I would not get perfection for less than a third the cost of the real deal.
And I didn’t, but you know what? The Zhumell 16mm, a.k.a., “the Happy Hand Grenade” wasn’t that bad either. Were the stars at the edge of that great big field perfect? No. There was astigmatism and other aberrations. However, much of the trouble had to do with me and my telescope and not the eyepiece.
A major reason for the ugly looking stars out toward the field edge was the astigmatism in my eyes. Another was due the coma inherent in an f/5 Newtonian mirror—no eyepiece, no matter how expensive, will fix coma; only a coma corrector can do that. All in all I was pleased. The big field was nice and since I don’t waste my time obsessing about the field edge, I thought I got my money’s worth.
Fast forward to today and things are even sweeter in the 100-degree arena. Meade (see my review of their 100-degree oculars in the August 2016 Sky & Telescope) and Explore Scientific are, again, upping the ante. Their reasonably priced 100s can, frankly, be astonishingly good. I was especially impressed by the ES 20mm. My friends and I did a shootout between it and the competition’s 100-degree 21mm a few years ago on the hallowed observing field of the Chiefland Astronomy Village and were frankly amazed. Was one better than the other? Hard, very hard, to say.
And there are new players coming onto the field with their own Chinese 100s: William Optics, SkyWatcher, and others. It’s an interesting time to be a dollar-conscious amateur astronomer with an eyepiece Jones.
So, should you pay the extra fare for the “best”? That’s for you to decide, but I’ll no longer be paying a premium for a relatively small increase in performance. All else aside, the “quality” of my vision means getting closer to perfection than what I get with less expensive eyepieces won’t help me much. Your mileage may vary, but I prefer to give up a mostly unobservable degree of improvement and use the money I “save” to pay my inevitable weekly bar tab at Heroes.
M64: The Blackeye Galaxy
Yes, the Blackeye Galaxy is spectacular, but it is a subtle spectacle. It can be detected in amazingly small backyard scopes—its magnitude of 8.52 coupled with a large but not too large size of 10’43” sees to that—but small scopes won’t show the dark patch, the black eye, near the galaxy’s nucleus that most observers long to see.
M64, located in the spring constellation Coma Berenices, is fairly easy to find without electronics, if not as easy as its predecessor on the list, M63. The best way to approach it is using magnitude 5.0 35 Comae. The star is almost halfway along a line drawn between Diadem and Gamma Comae, stars that should show up—if barely—in fairly poor suburban skies. 35 will likely require optical aid, but a 50mm finder will reveal it easily. When you have the star in the eyepiece, move 1-degree northeast and you should bump right into M64.
Your reward for hunting it down? The galaxy is undeniably impressive in a 4-inch on a nice night. In a medium power eyepiece, it’s a large oval of nebulosity that really “looks like a galaxy.” A 4-inch will also reliably show M64 is possessed of a small, near-stellar appearing nucleus. Alas, that is about it. Occasionally I’ve been convinced I’ve seen a hint of the black eye, the dust patch near the object’s center, with three and four inch backyard telescopes, but it’s just an impression I get when I use averted vision. Not something I can hold steady with direct vision.
Seeing the black eye easily takes at least an 8-inch. In the backyard, a C8 will turn it up, but it’s still not going to be something you can admire with direct vision. That will take a 10-inch on a good night at 150x and above. Wanna kick it up a notch? A larger scope under dark skies will begin to show the black eye isn’t a round black spot at all, but instead a curving arc of dark material. My C11 shows that fairly reliably at a dark but not crazy dark site. One year at the Georgia Sky View star party at Indian Springs State Park near Jackson, the C11 made this galaxy into an absolute thing of wonder.
M65: The Leo Trio (with M66 and NGC 3628)
Oh, M65 is good. Don’t kid yourself about that. M65 is slightly dimmer than M64 at an integrated magnitude of 10.25, but it is also smaller, 8.1’x2.1’, so it stands out well. That said, in the backyard on a so-so night, it’s more of a smudge that teases you with hints of detail than anything else.
M65 is easy to find manually thanks to its proximity to one of Leo’s bright “hindquarters” stars, Chertan, Theta Leonis. With Theta in the finder, scan two and a half degrees east-southeast and you should run across M65 without fail. You will also likely notice the similar (though hardly identical) M66. Which is which? M65 is the eastern galaxy and M66 is the western one.
While M65 is easy to see with a ten or eleven inch scope in the backyard—heck, it’s not really a challenge for a four or five—seeing detail is a little dicier. That takes dark skies and at least a ten-incher for me. Under suburban-country transition zone skies, there’s still not a wealth of detail to be seen in the galaxy. It’s a strongly elongated lens shaped object with a bright center. What it looks a lot like is a miniature Andromeda, M31. Under the best conditions with a 12-inch I get hints of a dust lane near the periphery of the disk, but it is not easy.
M66 at magnitude 8.92 and 9.0’ across its longest dimension appears similar in brightness to M65, but strikingly different in appearance. The most amazing thing for me is how easy it is to tell M66 from M65 visually even under rather poor conditions with a rather small telescope.
If you found M65, you can find M66, so no worries there. Once you are on the proper galaxy, what will you pull out? In the backyard, the most prominent thing is this SAB galaxy’s large, bright elongated, central region. That and a faint outlying haze is about all I get from the back 40, though. At high quality observing sites, the 10-inch or the C11 will begin to reveal at least one of M66’s huge, sweeping spiral arms and tantalizing dark details.
The true joy of M65 and M66 is in their “Leo Trio” guise, however. In addition to the two bright galaxies, there’s a third, dimmer one here, magnitude 9.48 (but looks considerably fainter than the Messiers) Hamburger Galaxy, NGC 3628. It’s a near edge-on, and when observed from dark sites with 10-inch and larger scopes it can show a prominent equatorial dust lane. If you have an eyepiece that can frame about 45’ of sky, you can get all three of these beauties in one field. Let me tell you, the view in my 10-inch Dobbie, Zelda, equipped with a 13mm 100-degree eyepiece, which easily frames all three, is stunning.
As you know, I am not the world’s greatest open cluster fan. But some I do like, like M67, Cancer’s “other” open cluster. It’s rich and it is different. It’s quite old for a galactic cluster, on the order of up to five billion years as a look at its color-magnitude diagram shows. Cool thing, though, is that this magnitude 6.9, 25.0’ cluster looks its age. M67 is a sprinkling of gently glittering amber gemstones set amidst Cancer’s lonely stars. Embers fading away at the end of time.
Finding M67 is as easy as falling off the proverbial log since the cluster lies near Cancer’s Alpha star, Acubens. While Acubens is not very bright at magnitude 4.25, it’s usually detectable naked eye from the suburbs when the Crab is riding high. When you are on it (a zero power finder working in tandem with your 50mm finder scope helps), just cruise 1-degree 45’ northwest and you will encounter this pretty group.
When you have M67, the first thing you’ll notice other than that it’s a nice, very nice, if somewhat subdued cluster, is that it is slightly elongated, and, more than that, that it is quite rich. A 10-inch under reasonably dark skies will easily show more than 100 suns here.
M68 is a very sweet little globular star cluster. Unfortunately, for some of you this Hydra object is a bit far south, declination -26. How far south is that? Well, about as far south as M83, the Southern Pinwheel. This is the last stop before you get to the land of Centaurus and Lupus, y’all. If, however, you’ve got a good view to the south you’ll like this one. It’s reasonably bright at magnitude 7.3, reasonably large at 11.0’, and loose enough to be easy to resolve without being so loose that it is dim.
The main problem for mid-northern-latitude observers hunting M68 without computers is that more than a few of them are unfamiliar with this far southern part of the sky. Best way to the glob? Probably by using Beta Corvi and Epsilon Corvi, both of which are bright. The cluster forms a near right triangle with the two and lies 3-degrees 30’ south of Beta (Kraz).
If, like me, you can get pretty far south before running into too much of the trash near the horizon, M68 can be a treat, even in a smallish scopes, as it was one night with my ETX125, Charity Hope Valentine, from the club dark site:
M68 is a pretty Shapley-Sawyer class X globular cluster in Hydra. It doesn't look as loose to me as its X rating would indicate. What I see is a somewhat elongated, very grainy appearing core. It is not close to culmination yet and is fairly low on the horizon and in the haze, but I can see quite a few tiny stars winking on and off around the edges of the central area. Best at 170x.
This globular, another of those that crowd along the base of Sagittarius’ Teapot (which believe it or not is now beginning to climb back into the sky at mid-evening), is middling good for me at magnitude 8.3 and 8’06” in size. And from more southerly latitudes than my 30-degrees it must be impressive. I doubt it would be a showpiece even if it were overhead, though. It’s a middle-of-the-road glob.
At least it is easy to find. Draw a line from Eta Sagittai through Epsilon, extend that line for another 2-degrees 30’ and you are there. Take it easy, though. If you are at a fairly high latitude, the glob might not jump out at you. Check the field carefully using a medium power ultra-wide eyepiece if possible.
With M69 in view, you are probably going to be pleasantly surprised at what you find—especially given me dissing the little guy. This Class V glob is small enough to remain bright, and not so tight as to be difficult to resolve. 150x in an 8 or 10-inch telescope from a passable site will just about always do it.
This Sagittarius glob is in many ways similar to M69. Same class, V, similar size at 8.0’, but a little dimmer at magnitude 9.06 and slightly farther south. So, the impression I get is “a lot like M69, but not quite as nice.” It’s a Messier, though, so “not so good” is still awfully good when compared to your average NGC globular.
If M69 is easy to find, M70 is Real Easy. Just draw an imaginary line between the Teapot’s base stars, Ascella and Kaus Australis. M70 is almost smack in the middle of the line. As with M69, don’t get too cavalier. If M70 is low in the sky for you, it may not be obvious in the field at first glance.
Despite its couple of minuses compared to the previous glob, the impression I get of M70 is “much the same.” It might be just a touch harder to resolve than M69 on a comparable night, but not enough to make much difference. 150x is a good power for me with the 10-inch.
So, what’s up next Sunday? We may take a week off from the Messiers. I’ve got a new piece of astronomy software here I’d like to tell you about, the new version of Deep Sky Planner, and it is my intention to do that next time. Rest assured, though, we will soon be back on the Messier trail.
Sunday, June 19, 2016
The Magic Ring
One of my Facebook friends asked me a question the other day. On the face of it, it was a simple and casual one, “Rod, do you still image the Messiers?” Sometimes the simplest questions turn out to be the most thought-provoking, however. I replied that, yes, I still take pictures of the M objects (and observe them visually as well). After sending my reply, though, there came another—internally generated—question, “Why?”
Because they are just so wonderful. Are there some objects in the NGC and other deep sky catalogs that are better, visually, than some Messiers? Yes. But the preponderance of beauty is in the Ms. Almost—if not quite—every one of them is a gem. Do I get tired of looking at them? That would be like asking whether I get tired of looking at Mona Lisa or reading Hamlet. I have never seriously observed a Messier without seeing something new in it—well maybe except for M40 and M74, but they are the only exceptions.
OK, forward we go…
We start this installment’s bunch with a bang, a real superstar. M57 has been one of my most beloved objects since I first hunted it down many a moon ago with my 4-inch Palomar Junior reflector. Not that I can say it really looked like much back then, not compared to what my telescopes of today will bring home, but, it was easy to find, it was obvious in the eyepiece, and it actually looked a little like the pictures in the astronomy books I checked out of my elementary school’s library.
Certainly M57 is a worthy target for three and four inch telescopes. At magnitude 8.8 and 3’48” across its longest axis, it is easy to see with a small telescope in the suburbs. You can see this corpse of a dead star, yes, but don’t expect too many details with a little telescope. At least you won’t have to worry much about finding it. It’s almost halfway between a line drawn between two of the little summer constellation Lyra’s most prominent stars, Beta and Gamma Lyrae.
In 4-inch and smaller instruments under less than optimum conditions—the inevitable summer haze that affects even Lyra with its nice northerly declination of +30—there is only so much you can expect. M57 will be immediately obvious, even in a fairly low power eyepiece; it’s over twice the average diameter of Jupiter and is not a planetary nebula that will masquerade as a fuzzy star. Unfortunately, all you’ll see easily is just that, that it is not a star. Its ring shape is elusive, even if you pump up the power.
At 6-inches of aperture, things get much better. It will be undeniable that M57 is a smoke ring, not just a disc. When seeing is good, it will also be easy to see that this ring is squished, that it is somewhat elongated. Finally, when you increase the power to 200x or thereabouts, you’ll observe the center is not empty, but hazy; this is a filled donut.
Frankly, the view will be much the same at 8-inches, though all of these things will begin to be easier. You’ll also note on the best nights that the “ends” of the Ring’s oval on its longest axis are not sharp, but diffuse. While, unlike some planetary nebulae, the Ring doesn’t offer strong color, you can still occasionally detect a blue-green tint in it on transparent nights, most easily with 8-inch and larger telescopes.
It’s at 10-inches that you can begin to hope for some lagniappe, including the faint star (magnitude 15 or so) that’s just outside the ring to the northwest. It’s a pretty good accomplishment to bring home that pesky sun, but it is not THE star. The Star is the Ring’s elusive central star, a white dwarf, the remnants of the sun that created the nebula.
Can you see the Ring’s progenitor with a 10-inch? Yes you can. I saw it summer before last with an humble Chinese 10-inch Dobbie. Was it easy? I wouldn’t call it easy, but it was not overly difficult either. A novice observer out there with us on the club field picked it up without much of a fuss when we told him what to look for. That’s the good. The bad is that the central star has regularly eluded me in 30-inch and 42-inch Newtonians.
|M59 and M60...|
How can the central star be easy with a 10-inch one night and impossible with a 42-inch another night? Some people think the star, which is nominally at magnitude 15 or thereabouts, is a variable. That’s possible, but I don’t really think that’s the answer. The problem is the Ring’s filled interior. If the donut hole were dark, the star would be fairly trivial. It is not; the interior is very much a light gray, and the contrast between it and a dim star is minimal.
So how do you see the central star? Really pump up the power, to 500x and higher. In the above mentioned 10, the star wasn’t there at 250x, but with higher magnification it swam right into view. To make use of high power, which spreads out the bright background in the Ring’s donut hole and increases contrast between it and the star, you will of course need good seeing. If the seeing is not good, the star will be invisible even in a very large scope. It will be smeared out of existence. Luckily, even in this day when weather patterns seem to be changing—and not for the better—I get good seeing with fair regularity in the summer and can often at least glimpse that fabled central star.
From the sublime to the ridiculous. Oh, Virgo’s M58, an SAB barred spiral galaxy, ain’t exactly ridiculous, it’s just that it’s in a whole other class compared to objects like M57. Not a bad class, mind you, it’s magnitude 9.66 and 5’54” across so it is fairly prominent for a galaxy. It’s just not liable to put your eye out.
How do you find this galaxy? Easy: push the M button on your goto telescope’s hand control followed by 5 and 8. I am not kidding. Oh, you can find it the old fashioned way with finder and chart even if you are a relative novice, but M58 is right smack in the middle of the cloud of Virgo galaxies at the heart of the constellation, between the arms of the maiden as it were. Best guide to M58? Probably magnitude 5 Rho Virginis, which is about 2-degrees to the southeast of the galaxy in this star poor area. You’ll need a detailed chart, of course, since even in suburban skies you’ll see multiple faint fuzzies in just about every field you land on here.
Once you are there, what will you see? With an 8-inch to 10-inch, you may see at least one more galaxy in the field, NGC 4564, but there is no doubt which one is M58; it is the big one. Is it also bright? I can see it from the backyard with direct vision with my 8-inch, but it is easier with averted vision. Naturally, it is more prominent in a 10. As with many galaxies, bright and dim, what it resembles an unresolved globular cluster: a bright core surrounded by fainter haze.
E5 elliptical Messier galaxy M59 is cool. Not just because it’s bright at 10.6 and shows obvious elongation n/s with dimensions of 5’24” x 3’42”, but because its field is just so beautiful. An 8-inch will turn up at least 3 galaxies here. In addition to M59, there’s M60, another bright M 25.0’ to the southeast, which is graced with a smaller companion galaxy, NGC 4647, 02’41” northwest of its center. M59 itself appears as a noticeably off-round fuzzball with a fairly extensive outer halo.
Once again, goto or digital setting circles are the way to go here. Sometimes, here in the heart of Virgo, it’s still hard to figure out which object is which, however. Luckily, the layout of these three bright galaxies is pretty distinctive, and once you orient yourself as to the way your telescope presents the field as compared to your chart—inverted, mirror reversed—it is easy to ID the fuzzies. Make it easy on yourself and use a computer charting program like Stellarium, which will allow you to flip or invert the field to match what is in the eyepiece.
Is M60 even better than M59? Perhaps. It’s got a brighter magnitude value, 9.8, but this 7’24”x6’0” E2 elliptical galaxy is not as obviously elongated. It trumps M59, however, because it has little buddy NGC 4647 beside it. An 8-inch telescope will have no difficulty picking up a faint nebulous patch beside the main object. Don’t see it? You are likely on M59 rather than M60, then. DSCs or goto are, again, the path to happiness here.
M61 is a face-on SAB spiral galaxy, and face-ons tend to be tough. Luckily, this one is fairly small and bright, 6’30” in diameter and magnitude 9.65, so seeing it is not much of a challenge. Not for a 10-inch in the suburbs. Want to do beyond just seeing it, though? A 10-inch under a dark sky can do well with this one, but a 12-inch is undeniably better.
At least it’s a little easier to find M61 than the run of the mill Virgo galaxy, it being in the western part of the constellation away from the greatest mass of objects. You’ll find M61 5-degrees north of Eta Virginis and about 1-degree 18’ northeast of a prominent 5th magnitude star, 16 Virginis. All in all, finding this one manually was a pleasantly easy surprise.
With the galaxy in the field, what you’ll see with a suburban 10-inch is a round subdued glow with perhaps a hint of a stellar-appearing core. A 12-inch makes the galaxy easier with direct vision but that is about it. Under dark skies with 10-inch and larger telescopes, you’ll see signs of spiral structure, and especially the galaxy’s most prominent, sweeping spiral arm.
Ah…summer’s coming in and that great celestial bug, Scorpius, is on the rise. Our next target, M62, a globular star cluster, looks like it ought to belong to the Scorpion, but it’s actually just over the border in Ophiuchus, in the southern part of that sprawling constellation. At magnitude 7.3 and 15.0’ across, M62 stands out well, or WOULD if it were higher in the sky for most Northern Hemisphere amateurs.
Yes, M62 belongs to Ophiuchus, but if you are finding it The Old Fashioned Way, use two of Scorpius’ stars to pin it down. The glob lies about 4-degrees northeast of the Scorpion’s body, and forms a triangle with two of his stars, Tau and Epsilon Scorpii. Assuming Scorpius is well over the horizon, and the haze and light pollution is not too bad, the M62 may show up in your finder as a wee fuzzy.
It M62 good? It would be if it were higher, but it is not. As is, in an 8-inch under the average summer conditions in the suburbs, you may have to settle for “grainy but not resolved.” A 10-inch at a dark site can bring out a satisfying number of stars in the halo of this somewhat compressed Type IV cluster.
We began on a good one and we end on a good one too, M63, the winsome Sunflower Galaxy. It is still a galaxy, however, despite the fact that it’s a Messier and has a reputation for being spectacular, so don’t expect “blindingly bright.” It is easy enough in a 4-inch, though, and can begin to show its sunflower aspect in a 10-inch under decent conditions given its bright magnitude number, 8.59, and reasonable size, 12’36”.
Finding this Canes Venatici object is easy due to its prominence and to its position about 1/3rd of the way along a line drawn between Canes’ Cor Caroli and the Big Dipper’s Alkaid. The galaxy is actually about 1-degree northeast of this line, but a little scanning with a medium-low power eyepiece should turn it up without much hair pulling.
A 4-inch telescope in the backyard will show you the basic features of this steeply inclined galaxy. It’s a prominent oval with a bright, small, but not stellar center. To see more, you will need a 10-inch and a dark site and a medium-high power ocular. With one, you can hope to glimpse the mottled, patchy, petal-like spiral arms that give rise to M63’s “Sunflower” moniker.
So..? The finish line is not yet in view; it’s a long way off yet, but I smell victory. What say we continue our M-quest next week, too?
Sunday, June 12, 2016
At the Messier Halfway Point
After this installment’s M-objects, we’ll be a little more than halfway through The List, or maybe considerably more than halfway through depending on exactly which objects you believe are genuine Messiers. Anyway, the star of this week’s show is, as I said last Sunday, the Whirlpool Galaxy, M51. I made a few remarks in the previous week’s article about this rather spectacular deep sky object, to include my choice of an effective telescope for viewing it, a 10-inch to 12-inch Dobsonian.
Why a Dobsonian? To begin, in this aperture, 10 – 12-inches, a Dobsonian is the most economical choice. Sure, there are a few expensive custom-made Dobs available in this aperture range, but they are far outnumbered by the inexpensive Dobbies of Synta and GSO. Is a Synta or GSO mirror the equal of a Zambuto? No, but the current imported mirrors are actually very good. It’s unusual to find one with a figure that’s not at least ¼-wave and often better, and one will serve well for deep sky observing (and may not be a slouch on the planets either). A 10-inch GSO or Synta Dobsonian can be had for around 500 dollars and is an incredible bargain.
At least as important as cost, for me anyway, is portability. A 10-inch or 12-inch fork mount SCT is a heavy telescope any way you slice it. A 12-inch Meade is frankly a beast best suited for an observatory. A 10 or 12-inch SCT OTA on a separate mount is easier to handle, if not that easy, but then you have to transport and set up a GEM (or other) mount too. I don’t mind doing that occasionally, but certainly not for an hour long Messier run from my backyard.
In contrast, a 10-inch solid tube Dob is easy and quick for most adults to transport and setup. The OTA will fit in the backseat of most vehicles, and all there is to assembling a solid tube scope is “plunk rocker box down, place tube in rocker.” This degree of portability does begin to ebb at 12-inches, admittedly. Carrying a 12-inch solid tube Dobsonian is doable for some people, but it is like wrestling with a water heater. Luckily there are alternatives.
One is the traditional truss tube scope. That is a good solution if one can be left assembled for transport to the backyard. Often that is not possible, not with the trad style truss scope. The tube assembly can be even more awkward and heavy than a solid tube telescope. And disassembling the tube to get the scope into the backyard and then reassembling it is a pain.
However, there are now 12-inch Dobsonians that are easier to handle than old-fashioned trusses and somewhat lighter than a solid tube telescope. I’m talking about the collapsible tube telescopes from Synta. Another possibility if you have considerably more bucks to spend is the ultra-light Dobsonians, which are available from several makers.
A Dob is a good choice for attacking M51 or any other Messier, but it’s one that leaves some beginners uneasy: “Don’t I need goto and tracking?” Both those things can enhance your experience, but goto/tracking is no longer the exclusive province of SCTs. Synta produces Dobsonian telescopes under its SkyWatcher brand and for sale by Orion that feature both things. And an un-driven scope can be equipped with digital setting circles that make finding easy. Isn’t it hard to track an object by hand at higher powers? Not if the telescope is properly made. I find tracking at 500x easy with my 10-inch GSO Dobbie.
None of this is to say you must have at least a 10-inch telescope to have fun with M51. A dark sky can allow much smaller scopes to do a good job on the galaxy and its companion. My experience, however, is that 10-inches is where it starts getting really good.
OK, let’s go, beginning with M50…
M50, the Heart Shaped Cluster
Do you like open clusters? You don’t? OK, OK, but this is a Messier open cluster and at least somewhat removed from the “dim, not well detached” NGC opens that provoke your scorn. M50 is bright at magnitude 5.9 and reasonably compact at 15.0’ across its longest dimension. It’s visible easily in finders and quite rewarding in medium aperture telescopes.
Since the cluster is easy in a finder, locating it is trivial on those deliciously dark and clear winter evenings after a front passage. Scan some 5-degrees northeast of Theta Canis Majoris, the big dog’s “nose” star, and you should run across M50 without a fuss. This is a fairly star-rich area, but M50 is the only open cluster of any prominence in the region.
On target, your reaction will likely be much like mine, “Not too shabby, not too shabby.” A 10-inch will show maybe 25 bright stars and perhaps three times that many fainter ones at medium magnification. This is the Heart Shaped Cluster because its looping star chains seem to outline a Valentine’s Day heart. I sometimes have trouble making out the supposed “shapes” of open clusters, but even I see a heart here. Look for the prominent red central star in the midst of M50’s suns.
M51, the Whirlpool Galaxy
And here we are at the Whirlpool. What do you need to know about it most of all? That it is beautiful, but also subtle. Its magnitude is 8.1 and its size is 11’12” x 6’54”, yielding a surface brightness of somewhere around 13, which doesn’t sound too bad, but remember you are after details, and those details, the spiral arms, the dust lanes, the “bridge” between it and its interacting companion galaxy, NGC 5195, are not easy. Sure, I’ve seen the galaxy from heavy light pollution, but only as two blobs, a bigger one and a smaller one, and most of us want the Whirlpool to be more than a “been there” object.
To do anything with M51, you have to get there, of course, and without a goto computer and in a moderately light polluted sky, that can be somewhat difficult. What works for me is a 50mm finder and a pair of 7th magnitude stars that lie 3-degrees 21’ northwest of bright Alkaid, the “end” star of the Big Dipper’s handle. M51 is just 19’ farther to the northwest and closest to the southeastern star of the pair. If you are observing from the suburbs, pay close attention to the field. M51 will not likely jump out at you.
So what will you see with a 10 – 12-inch telescope? That depends. From my club’s (semi) dark site in the suburban-rural transition zone, I can always make out spiral structure with the 10-incher, but, remember, I’ve been looking at this thing for nearly 50 years. If you are new to the Whirlpool, spend plenty of time on it, use a variety of magnifications, and employ the tricks—like averted vision--we discussed a while back. Beyond basic spiral structure? I can usually see parts of the bridge of material between the two galaxies, but it is not complete. I can also, on a good night, a superior night, see hints of the Whirlpool’s convoluted dust lanes.
|M52 and the Bubble...|
With a larger telescope, you will see more from a site like my club’s, but not a whole lot more. What this galaxy, like most galaxies, needs is a dark sky. The best view I’ve ever had of this object was with a modest instrument, my old 12-inch telescope, but that scope, Old Betsy, was sited under the very dark skies of the Texas Star Party in 1999. From there, the complete bridge was obvious (if still not blinding), and I wasn’t just able to see dust/dark lanes, I could see their edges were not smooth, but “curdled.”
M52, the Salt and Pepper Cluster
Cassiopeia’s M52, another open cluster, is not good and it’s not bad. What makes it stand out is a superb neighborhood. While a 10-inch is once again probably optimum, even a 4-inch will do a good job of capturing this magnitude 6.9, 16.0’ group.
Look for M52 about halfway along and 45’ west of a line drawn between Beta Cassiopeiae, Caph, and Iota Cephei. While not as prominent in a finder as M50, you should still be able to see something here with a 50mm.
M52’s main claim to fame—if any—is its legion of tiny stars; up to 100 are visible in medium aperture telescopes at medium-high magnifications. There’s a red central star, but the chief impression is “tiny, closely-packed stars,” which is what gives the effect of a sprinkling of salt and pepper on a dark background.
The neighborhood I mentioned? If you’ve a dark enough sky and a 10 – 12-inch telescope and maybe a nebula filter, move your telescope 36.0’ to the west and you will come upon the famous Bubble Nebula. While it is easy to image, it’s not quite so easy to see any of the nebulosity visually, much less the bubble shape, without dark skies and good transparency.
M53 has, to me, always been a herald, a herald of the return of the summer sky and its hordes of globular star clusters. This spring glob is not nearly as good as its more easterly mate, M3, but after a months of a globular shortage I welcome it, and it is pretty good. Better than puny little M79 anyway. In a dark sky and riding high, this magnitude 7.7, 13.0’ across ball of suns is pretty in a 10-inch or an 8-inch if not overwhelmingly pretty.
For once, finding is not a concern. If your site is at least good enough to show Coma Berenices’ magnitude 4.3 Alpha star, Diadem, you are in like Flynn. M53 lies a mere degree and a half to the east. On a decent night, the cluster should appear as a slightly fuzzy “star” in a 50mm finder.
When you are there, what will you see? From the average suburban backyard, all you’ll find in the eyepiece of your 6-inch and smaller scope is a fuzzball. A prominent enough fuzzball, but a fuzzball. An 8-inch will give you a cluster that wants to break into stars, but can’t quite do it. Grainy, yes, resolved, no. In 10-inch and larger telescopes, you get what you came for: plenty of tiny sparklers.
If you have really good skies and an 8-inch or larger scope at your disposal, look for M53's companion globular NGC 5053, which is loose and difficult. This open cluster-looking glob lies about a degree southeast of M53.
Here’s another glob, Sagittarius' M54. At magnitude 7.7 and a size of 12.0’, this one is hardly a spectacle. That’s largely thanks to the relatively large distance between us and this fairly compressed (Type III) star-ball. It’s some 36,000 parsecs distant and looks it.
Luckily, finding M54 is trivial if Sagittarius is decently high in your sky. It is found on the “handle” side of the Teapot’s base and is 1-degree 42’ west of Ascella, the teapot’s “leftmost” bottom star. Tread carefully, especially if your location is at a higher northern latitude. In horizon haze M54 will definitely not be prominent.
What it will be is a fuzzball. Not just in 4 – 6-inch telescopes, but in 10 – 12-inchers as well. As above, it is tight and far away, and while it begins to look grainy in 12-inch scopes, I’ve never achieved much resolution in even a 16-inch under suburban skies.
This is yet another Sagittarius globular. Alas, it’s no M22, though it might look quite a lot like that fantastic glob if it weren’t so poorly placed for Northern Hemisphere observers. As it is, this magnitude 7.42, 19.0’ group is sadly diminished.
M55 can also be difficult to find “manually.” That’s because much of the time it is in the treetops and it is also located in the rarely visited southern portion of Sagittarius well removed from the teapot. Position your telescope 8-degrees southeast of Ascella, and scan carefully with as low power an eyepiece as you can use given the probable brightness of the sky background in this part of the constellation. M55 is a loose one, a Type II, so look for something that appears to be a round and rich open cluster.
The actual appearance of M55 will depend on how high it is in your sky, the transparency in its area, and the aperture of your telescope. This is really an object for a 10-inch at least, and on a good night down here in the southland, many teeny stars are revealed in M55. It ain’t exactly a spectacle, but it’s worth your time under the right conditions.
Yes, there are Messier globular star clusters and then there are Messier globular star clusters. M56 is most assuredly not an M13. Or even an M30 or M53, though the cluster’s specs don’t sound that scary. It shines out at magnitude 8.4 from its lair in Lyra and spans a mere 8’48” of space. The problem is that it’s a Shapley Sawyer Type X. A XII is the loosest type, so M56 is much like NGC 5053, if not quite that bad—5053 is an even looser XI and is considerably dimmer.
But, yes, M56 can be tough; it was amazingly so for me when I hunted it one long ago night from my parents’ suburban backyard with my 4.25-inch Palomar Junior reflector. It was a Messier globular and Lyra was riding high. Ought to be duck soup, right? I got the scope on the cluster’s approximate position with the aid of Norton’s Star Atlas. Nothing. Nowhere. Could my aim be that far off? No. I finally spotted the little devil as a dim, very dim, round glow. That was M56?
It’s easy to get on M56’s spot without a computerized telescope as it is conveniently placed approximately halfway along a line drawn between Albireo and Lyra’s Gamma star, Sulafat. It’s actually a little bit outside that line to the east by about 45’ and slightly closer to Albireo than Sulafat. If you need further direction, a fairly prominent magnitude 6 star, SAO 68040, is 24’ northwest of the cluster.
What do you get for your efforts? From the average backyard, not much; in a 6-inch, M56 remains a smudge not much better than what I saw in the Pal Junior. An 8-inch will begin to resolve a sprinkling of stars at about 150x, but still “mostly a round glow.” Things get better in Zelda, my 10, which, when I increase the power to 200x, begins to bring home something that looks like a globular. To get more than that the solution is a dark site.
With (now sold) Old Betsy, M56 was quite attractive from darker skies like the Percy Quin State Park of the 1990s, the initial home of the Deep South Regional Star gaze. Under those good but hardly perfect conditions, the cluster began to at least approach M53. In addition to plenty of resolved stars in the outer halo, the 12-inch would show M56 has a distinct, brighter, triangle shaped core.
How did you do? What did you see? How did you see it? I’d love to hear if you’d like to post your comments. I am not able to respond to every single one, but I assure you I do read them all.
Sunday, June 05, 2016
A Brief Intermission…
As usual when I am on the road (which will happen more than a few times this summer), you are mostly being cheated out of your accustomed Sunday read. That may be all to the good this time, however. It gives you a chance to get out and observe the star object in my next batch of Messiers, M51. The Whirlpool Galaxy is one of the greats, and I’d like to compare notes with you.
What do you need for this spectacular but nevertheless somewhat challenging galaxy? It can look good in almost any telescope, but it cries out for a dark sky. Assuming you have that dark sky, my telescope choice is a balance of aperture versus hassle, a 10 – 12-inch Dobsonian, with the pick for (lazy) me being a 10-inch.
Anyhow, get out to your club dark site or whatever and see what you can see of its spiral structure, dust lanes, and other features and those of its companion galaxy, NGC 5195. Can you maybe even spot some of the other galaxies in the field or nearby (they are admittedly dim and small and likely a challenge for a 25-inch big gun)? You’ll find out what I was able to scope out next week, and I’m hoping you will post your observations in the comments section thereafter.
Sunday, May 29, 2016
Here’s Exactly How You Do It: Imaging Jupiter (or Mars or Saturn)…
|Jupiter under poor seeing with the setup described herein...|
I’ve posted articles concerning planetary imaging more than once in the past, but in them I’ve always given you alternatives, “You can buy software A or software B. You use telescope A or telescope B, you can try camera A or camera B.” But I’ve come to realize people getting started in photographing the solar system may, at first anyway, just want to be told what to do. What exactly can you buy and download to image the worlds of the Sun and how exactly you use it. No choices, just a simple system that works.
So, before you write me to ask, “Well, how come you didn’t mention this telescope or this camera or this software?” I know there are alternatives to the setup I am going to describe. What I am doing is telling about a system that will work, and that you can modify as your experience grows.
One last caveat: getting good pictures of the planets depends on one thing more than anything else: seeing. Atmospheric steadiness. That trumps telescopes and cameras of the most expensive sort. If you live in an area with constant poor seeing, there’s only so much you can expect. Take heart, though. Most people don’t live in locations like that. Most peoples’ seeing steadies down occasionally at least. Keep an eye out for the sort of weather that will bring steady air, like stagnant high pressure domes, and be prepared to take advantage of it.
How much will it cost to get into planetary imaging? Not much if you already have a suitable telescope and mount. If you don’t, expect to spend as much as 1000 – 1500 bucks for a usable scope and mount, or as little as 300 – 400 for a telescope alone.
OK, let’s get to it. First step is accumulating the gear you need…
I don’t make a secret of the fact that I don’t use SCTs as much as I used to, but when I go after the Moon and planets, I go back to them. And specifically the 8-inch Schmidt Cassegrain. It brings one important thing to the table. Lots of focal length. You can get to the 4000mms of focal length that is where you begin for high resolution Solar System pix with the addition of a simple 2X Barlow. One also has enough light gathering power to make exposures reasonably short, a must if you are to defeat seeing. Finally, a Meade or Celestron 8-inch SCT is short and light and does well on less expensive mounts. Get an 8-inch SCT.
|Meade flip mirror on SCT...|
Naturally, you’ll need a driven, tracking mount. You’ll also find goto speeds things up a lot. You wouldn’t think it would be difficult to get Jupiter or Saturn in the field the old fashioned way with a finder, but it is. It’s can be hard even if you have a flip mirror. A modern goto mount can put your quarry on the small chip of a planetary cam every stinking time.
Alt-azimuth or equatorial? A driven alt-azimuth mount is usable, but even if you take pains with the goto alignment (a good goto alignment improves an alt-az mount’s tracking), the tracking will be worse than that of a decently polar aligned GEM. A German equatorial mount makes life easier, so use one. Luckily they are cheap. A goto CG5 style mount, whether the ASGT Celestron CG5 (used only), the newer VX, the Meade LXD-75 (used only), or the new player, the Bresser mount from Explore Scientific, are inexpensive new and very inexpensive used. So, get a CG5 class GEM.
The requirements for a planetary cam, the basic requirements, are two: a small chip and small pixels. Quite a few cameras in all price ranges fulfill those requirements, but few do it better than the ZWO Optical ASI120MC. The “C” stands for color, as in one-shot color, which will make your life easier when you are starting out. Just because this camera is inexpensive new, less than 200 dollars, don’t think it is a slouch when it comes to performance. It will deliver up to 100fps, frames per second if you keep the size of those frames small (see below). So, get an ASI120MC.
You’ll need to double your SCT’s focal length by placing a Barlow lens ahead of the camera. Which? Luckily, I’ve seen very few poor quality Barlows of late. My choice for you is good, but it is also cheap, the famous Orion Shorty. I’ve used one for years and there is no downside to it.
You don’t need too many, but you need some. First and foremost, you need a flip mirror to make initial centering of planets easy, even with goto. This is a special star diagonal with a camera port on its rear and a mirror that can be flipped up and down. Flip it down to center the target in an eyepiece, flip it up to send the images out the rear port to your camera. Flip mirrors can be adjusted so that what’s centered in the eyepiece is centered in the camera, and what’s in focus in the eyepiece is in focus in the camera. Which one? My choice is the SCT specific Meade flip mirror, but it’s apparently no longer being made. That being the case, get this Vixen flip mirror; it will work fine, but it requires the purchase a 2-inch visual back for your SCT if you don’t have one.
Since planet-cams must be used with a computer, you’ll need one. Any modern PC will do; image acquisition and processing software is much easier on computer horsepower than a modern game like Doom, for example. You’ll either want a Windows PC or a Mac that can run Windows software, and naturally the computer should be a laptop since you’ll be using it outside. My choice is the simple and reliable Toshiba Satellite.
You’ll need to install two programs on that computer. One to operate the camera, and one to process the resulting .avi movies into stacked still frames. For camera control, get FireCapture. It’s free, and while it does tons of stuff, up to and including generating ephemerides and guiding a telescope mount, it is easy to use in simple point and shoot fashion. Its user interface is clean and simple, and it includes a camera simulator so you can play with it indoors. Yeah, get FireCapture.
When you shoot planets, you shoot .avi motion picture files. When done, you stack the (good) individual frames of those movies into finished still pictures and perform processing functions like sharpening the resulting stills and adjusting their histograms (contrast and brightness). The program that will do that is another piece of shareware, Registax. It is mature and easy to use in a basic fashion.
Odds and Ends
You’ll need an IR block filter for a one-shot color camera or images will be way too red, but the filter that comes with the ZWO camera is quite sufficient. All else you’ll need to buy is a longer USB cable, since the one that ships with the camera is a bit too short. Get a 10-foot USB 2.0 AM-BM cable (from your local BestBuy perhaps).
|Exposure Controls on FireCapture...|
Putting it together
The rest of this is going to be surprisingly short and sweet. To begin, set up the telescope as you normally do, but with the flip mirror on the rear cell instead of the normal diagonal. Use a crosshair eyepiece in the flip mirror, one that will yield a power of about 160x, a 12mm f/l eyepiece, that is. The Barlow goes into the camera port and the camera is inserted into the Barlow via its included 1.25-inch nosepiece. You can hook up the camera’s USB cable now if you like or wait till you are done with the mount alignments. You might also want to connect a serial cable to the mount if you want to be able to adjust the telescope’s aim with the computer.
OK, next you’ll either polar align or goto align. If you are using a Celestron mount, I suggest you do the hand control’s built-in AllStar polar alignment routine to ensure good tracking. To do that, you’ll need to do the goto alignment first. If you are using another brand of mount, you’ll normally do a polar alignment first. That doesn’t need to be a drift alignment, but should at least be a careful alignment with the GEM’s polar scope. If the hand control has a polar alignment routine like Celestron’s, use it.
Now, goto Jupiter (or Mars or Saturn or the Moon) and center the image in the flip mirror using the reticle eyepiece. At the computer, bring up FireCapture. There are a heck of a lot of options, but we only want to use the program in the very simplest manner and we’ll mostly be using the Control (exposure) section on the upper part of the sidebar. Adjust the gain slider there until it’s at about 75%; that will prevent images from showing the odd artifacts that can result from lower gain settings. Then, adjust the exposure controls until the planet looks almost bright enough but not quite, so that it looks just slightly underexposed.
|All stacked in Registax...|
Next, center the planet precisely. If you set up your flip mirror correctly, Jupiter should be in the frame, but probably not centered. Center it either with the HC or with an onscreen HC. If you have ASCOM installed on the laptop, use its virtual HC for centering. Just go to ASCOM in the settings portion of the sidebar by clicking the little ASCOM icon, check “initialize telescope interface,” and select the mount (and check “show hand control”) as per normal with ASCOM. If that sounds too complicated, just use the real HC for centering. An extension cable is helpful for that so you can sit at the computer when using the HC.
Focus up precisely. Again, if you set up the flip mirror correctly, Jupiter should be close to being in focus, but probably not exactly in focus. One help here is Motofocus. I had JMI’s Motofocus motor on my old Ultima C8, Celeste, and what a joy it was to sit at the PC and watch the display while focusing with a remote control. Otherwise, trot to the scope, adjust focus a bit, squint at the computer, and repeat as needed till Jupe is as sharp as you can get him (if there’s a Galilean Moon in the field, that’s a great focusing “tool”).
Finally, decide if you want to use FireCapture’s ROI, “Region of Interest” feature or not. If you engage this by clicking ROI in the “Image” portion of the sidebar (very top), and have selected “Jupiter” in the exposure section, Firecapture will crop the frame to a size just big enough to contain Jupe. That will allow the program to deliver much higher frame rates than you’d get at the ZWO’s full resolution. As long as tracking is good enough to keep Jupiter in the field for a minute to a minute and a half, use ROI.
There are two other settings you need to check. Make sure “debayer” is NOT checked in the Options section of the sidebar. As you may know, one-shot color cameras use red, green, and blue filtered pixels to produce color images. Normally, these pixels are combined on the fly to make a color image, they are “debayered” as you shoot. FireCapture, however, allows you to forego debayering, to shoot the avis as, basically, black and white images, and debayer them, convert them to color, later. This saves computer processing power and allows for a higher frame-rate. Also, check in the capture section to make sure "avi" is selected as the file type.
That’s the preliminaries. Now, just click the record button in the Capture section of the sidebar, and record some Jupiter movies. How long? About 1-minute is pretty good, especially if you are using ROI. That will give you plenty of frames to play with but not result in huge files that can be a problem. Shoot plenty more sequences, aiming for getting footage during the best seeing (best circumstances are shortly after dark with the planet above 30-degrees). When you’ve got some sequences that appear to capture the planet when it’s steady, you are done.
Next morning, the first task is to convert the .avi movies to color. Do that using the Debayer app in the FireCapture directory (put a shortcut to it on your desktop, since you will use it frequently). Open the little program, leave all its settings at their defaults, and select and then debayer all the .avi files. Debayer will place color versions of the .avis in the capture directory of FireCapture (you can specify the directory in FireCapture’s setup section before you do your captures).
Now comes stacking the best frames from the sequences with Registax. You will more than likely be a little daunted when you open the program for the first time. Don’t be. There are lots of options and adjustments, but you really only need to perform a very few actions to use the program in the most basic fashion:
- 1. Click “Select” (button on the upper left of the display) and choose the first debayered file. If Registax asks if you want to process it in color, respond “yes.”
- 2. Click the Align tab (below select), and push the “Set Align Points” button.
- 3. Click the Align button.
- 4. Click the Limit button when the align process is done.
- 5. Click Stack.
- 6. When stacking is finished, click “Save Image.”
- 7. Click the Wavelets tab. This is where it gets interesting. The famous Registax Wavelet filters will reveal details you wouldn’t dream were in the stacked image. How do they work? That’s a story for another day. For now, just check the boxes and adjust the sliders as shown here. This is a good starting point. Click “do all,” and see how the image looks. If it looks over processed, try backing off the sliders some.
- 8. There is no “8;” you are done. If you like, you can process Jupiter further with Photoshop or the program of your choice. Don’t have an image processing program? Registax has image processing tools. They are not as easy to use as those in Photoshop, but they work.
Sunday, May 22, 2016
The Messier VII: The Greatest
Before we get to the Great Nebula, let’s talk about “how.” We’ve talked about why novices (or anybody else) might want to take on the Messier list, and we’ve talked about “what,” as in what sort of telescope to use on these deep sky wonders. Now we will address “how” as in “How do you look at ‘em?” What are some tricks and tips for seeing as much of these legendary objects as possible?
The most important thing you can do to improve the appearance of the Messiers, the galaxies and nebulae especially? Naturally, “get to a dark site.” But what if you don’t have a dark site? Or want to observe more often than on once or twice a month runs at a club dark observing location? You can to some extent darken your backyard sky.
The easiest way to do that is with a trick many novices—and more than a few old hands—don’t know: increase magnification. The problem with seeing dimmer objects from the backyard is one of contrast. There is too little contrast between Messier object and the sky background in the eyepiece. The sky is nearly as bright—or as bright—as the M, and the deep sky object is rendered invisible or nearly so.
How do you fix that? Bump up the magnification. Increasing power spreads out the background skyglow, making it less intense. It will also dim the Messier, but often it still provides increased contrast and improves the view. Sometimes a lot. Experiment with a variety of magnifications on each object, but what you want is a power that dims the background but still leaves sufficient space around the object. If you kick up the power so much that the DSO fills the field, there will, again, be a lack of contrast. There will not be enough dark sky around the object to provide contrast.
Another way to darken the sky is to use Light Pollution Reduction (LPR) filters. I have an in-depth article on the subject of deep sky filters coming up in the August issue of Sky & Telescope, so I will refer you to that. Here, I’ll just say filters can make the difference between seeing and not seeing dimmer nebulae.
The next two tips have to do with physiology of the human eye and brain. The most important of the two is called “averted vision.” You’ll find that when you look off to the side of a faint object, look away from it instead of directly at it, you see dimmer features. That’s because looking off to the side of an object brings the eye’s dim light receptors, the rods, which are located around the retina’s periphery, into play.
At first it may feel odd or awkward to look away from the quarry instead of directly at it, but with a little practice you’ll get used to that. Under some circumstances, averted vision may allow you to see two or even more magnitudes dimmer than looking straight at the target and employing only the eye’s cones, the bright-light color receptors.
Jiggling the scope won’t give as much of a gain as averted vision, but it will still yield some improvement. The human eye-brain has an easier time seeing moving objects than stationary ones. That is probably evolution at work. Being able to see moving objects well—like a stalking leopard—would be a survival mechanism. So, tap the scope tube lightly, introducing some vibration, and you may be able to bring home details that were formerly invisible.
What can improve the performance of your eyes even more, perhaps, than the two previous techniques? Allowing them to become as dark adapted as possible, allowing your eyes’ irises to open up as much as possible. Yes, the sky is bright from the backyard, but if your eyes could obtain some dark adaptation, you would see more. What prevents that isn’t really the bright sky so much as it is ambient light, light from nearby sources. Your porch light, the neighbor’s yard light, etc.
What you want to do is rig up some means of shielding yourself and your telescope from intrusive ambient lights you can’t shut off. You can build light shields to shade the scope—I used to construct muslin covered stage flats for that purpose—or you can go simpler and more portable with a sheet of black cloth. A square of black nylon draped over your head can work wonders. What do you do to retain your night vision when you aren’t at the eyepiece? You could try Orion’s silly-looking red-tinted goggles, but cheaper and perhaps more effective might be an eye-patch from the drug store.
Finally, keep that bad ambient light out of the telescope. Most refractors and catadioptric telescopes have dew shields sufficient to keep ambient light out of the optical system. Newtonians are another matter. Modern fast Newts typically don’t have much tube ahead of the secondary mirror, so rig up a tube extension of black material of some kind—plastic, cardboard, whatever—to keep stray light off the secondary mirror.
Check the rear of a reflector, too. The primary cell may have some openings—a good thing where cool down is concerned—which can admit light reflected up from the ground. Rig up a cardboard baffle you can tape or Velcro over the rear of the tube to keep ambient light out of that end of the OTA when cool down is done.
With this arsenal of observing hints and kinks in hand, let’s tackle the next group…
M42 The Great Nebula
And great it most assuredly is. Along with the top globular star clusters of summer, M13 and M5, this is probably the greatest, most spectacular Messier of them all. This HII region, this emission nebula, shines with an integrated magnitude of 4.0, so, despite a size of at least 1-degree 30’ x 1-degree, it is seriously bright. It is, in fact, easily visible naked eye even in the city as the slightly fuzzy middle star in Orion’s sword.
Finding? Since it's a naked eye object, once you know what that fuzzy star represents you’ve found it. As I discovered when I was a little bitty kid with a 4-inch Palomar Junior Newtonian. I was hoping to get a copy of Norton’s Star Atlas “soon” so I could begin seeing deep sky wonders, but to my delight one cold December night, I found star charts are not needed for all Ms. I got curious about that funny star in Orion’s sword, pointed my little telescope to it, and there—OHMYGOD—was the Orion Nebula in my 1-inch war surplus optics Kellner eyepiece.
I won’t reiterate the descriptions of M42 found in a thousand books. I’ll just point out a couple of particulars I don’t hear much about. Yes, the nebulosity is great. Yes, there’s the Trapezium and the other fascinating stars enwrapped in that nebulosity. But what I tend to look at/for more than those things these days are the dust lanes and the nebula’s color.
Up the magnification and start exploring the area of the “fish’s mouth,” the dark bay in the nebula near M43, the companion nebula. This area is criss-crossed by many brownish (in images, anyway), dusty tendrils, and tracing them out in the eyepiece can be a fascinating pastime.
Color? Oh, yeah, I know the party line, “M42 may occasionally appear faintly green in medium aperture telescopes, and large aperture reflectors can sometimes show brown tinges that represent the nebula’s pinks and reds.” That’s true under normal circumstances, but on special nights, and I am not quite sure exactly what makes some nights special, M42 can literally appear stoplight green. Not faint green, but bright green. In an 8-inch or even smaller telescope.
How about trying Light Pollution Reduction filters on M42? I never use them much on Orion. Even in light polluted backyards it holds up well thanks to its brightness, and I prefer its look without an OIII or UHC filter. One of those may be of use when you are seeking fainter details, however. Start with the UHC.
M43, M42’s little buddy, is a smaller comma-shaped patch of nebulosity surrounding the magnitude 6.75 variable star Nu Orionis. M43 subtends 20.0’ x 15.0’ and glows at magnitude 9.0 (that’s the value usually given, but the central area is brighter than that). Not only is M43 interesting in and of itself; it’s a good indicator of the quality of your sky. If you can make out the comma shape easily in a medium aperture scope, you’ve got a good night ahead of you.
What’s to see here, about 10.0’ northeast of the main Orion Nebula? Quite a bit beyond the nebula’s basic shape. Under good skies with a magnification of 250-300x, there are plenty of details available. This, as above, is the area of dusty clouds, and you’ll see them encroaching on the south-southeastern edge of the nebula. You’ll also see the comma’s edges are wispy and complex and deserving of considerable attention. Like the main nebula, I’ve never thought that an LPR filter of any type improved the appearance of M43.
Ah, yes, the good, old Beehive, one of two Messier open star clusters in Cancer. M44, AKA “Praesepe” (“manger”), is a bright one, glowing with a combined magnitude of 3.10. Alas, it is also a large one, extending 1-degree 10’. That makes it proper fodder for big binoculars or a richest field telescope, not something like an f/10 C8. You need considerably more than 1-degree of field to make this one look good, you need a couple of degrees in order to put some empty space around the cluster’s stars.
If you can see the dim constellation Cancer the Crab, you are in like Flynn when it comes to finding. M44 lies in the middle of the triangle formed by Eta, Gamma, and Delta Cancri. If these stars are difficult to make out, it’s still easy enough to locate the target. Just point the telescope in the general area where the center of Cancer is or should be, and your 50mm finder should reveal the cluster without a fuss. In fact, it’s easy to see naked eye from medium dark sites on transparent evenings. In the olden days, people gauged the weather by the appearance of the Beehive. If it was easy to see, nice days were ahead. If not, storms were coming.
When you are on the correct spot, a 6 – 8-inch RFT will show a loose group of about 40 – 50 suns arranged in a slightly oval shape. 70 – 80mm binoculars will real maybe half that number. To me, M44 always looks slightly yellowish, which is understandable given the group’s fairly advanced age (for a galactic cluster). It is rife with red giants.
Don’t put that RFT or binoculars away. The next one is another big one, M45, the famous Pleiades, the Seven Sisters, the daughters of Atlas. Just about everybody has seen this huge (1-degree 50’) and bright (magnitude 1.2) galactic (open) cluster. Almost all my freshman astronomy students know it, though they usually think what they’ve seen is the Little Dipper thanks to the group’s brighter members forming a slightly squished dipper asterism.
Since you won’t have to hunt M45, you can give this group plenty of telescope time. In my old StarBlast RFT or my even older Short Tube 80 refractor, the Pleiades were simply stunning. Even an 80mm telescope brings in hordes of dimmer suns in addition to the bright sapphires that are visible naked eye. There’s something to be seen here in addition to cluster stars as well: reflection nebulosity.
The nebulosity, which is brightest around the cluster star Merope, thus giving it its name, “The Merope Nebula,” is extensive, but it is also dim in the way that only reflection nebulosity can be. It’s easy to image, as in my picture above, taken with an 80mm APO last autumn, but seeing traces of it visually requires a dark site and good transparency. Even then, it’s hard to be sure whether you’re seeing the nebulosity or not. The time-honored analogy is “baby’s breath on a mirror” and that is true in spades. By the way, the Merope Nebula does not represent the remains of the cloud that formed the star cluster; it’s just an area of dust and gas the group is currently moving through.
Y’all know I love bonus objects, deep sky objects with another deep sky object close at hand. In this case, really close at hand. M46 is a nice enough open cluster, mind you. 50+ stars are visible in an 8-inch as a rich group 20.0’ across shining with a combined magnitude of 6.10. On the other hand, the cluster is in an obscure constellation (for novices), Puppis, and is a smidge low for more northerly observers at a declination of -14. There’s that bonus, though, and that makes M46 over the top wonderful.
First you have to find M46. As always, the most efficacious method is just to punch in M-0-4-6 on the hand control. Can’t do that? It forms a long triangle with Eta Monocerotis and Sirius, and you really won’t need much more guidance than that. Under slightly putrid skies it still shows up as a smudge in a 50mm finder. Just don’t confuse it with M47, which is only 1-degree 20’ to the northwest. If the cluster in the eyepiece has a wide range of star brightnesses, with a couple of really prominent ones, you are on M47, not M46.
The cluster itself is a nice one, a basically round and rich group that can show as many as a hundred stars to a 12-inch telescope. There’s a small range in star brightness, most of them being of magnitudes 7 – 9, and that gives the group a substantial, solid looking form; it is well detached from the background. It’s little NGC 2438 that is the prize here, however.
NGC 2438 is a small, 1’10” planetary nebula that looks like a perfect miniature of the big ring, M57. While it’s somewhat dim at magnitude 11.7, the small diameter keeps it easy for small aperture telescopes. I’ve been able to prise it out with an 80mm refractor at 150x. If you’re having trouble finding it, looks for a funny-looking double star about 5’ north of the clusters center. The double looks funny because the planetary nebula is involved with it.
M47 is good, fine, alright, but to tell you the truth, I’d seldom look at it if it weren’t for nearby M46. It’s an OK, cluster, but just OK. Because of the large brightness range of its stars—there are several magnitude 4 – 5 suns in the field—it just doesn’t look as nice to me as M46. The brightness range makes it appear sparser than it actually is, and it is less rich than M47 to begin with.
If you can locate M46, you can locate M47. In your 50mm finder, it will be the cluster to the northwest, and will look brighter given its magnitude of 4.40 coupled with a modest size of 25.0’. Still not sure? It is the group that appears more resolved in a 50mm finder.
When you are on M47, you’ll note it’s basically shapeless, but that the bright stars at its center form a dipper shaped asterism, sort of like a miniature Pleiades or an M39. The view is similar in 8 to 12-inch telescopes, with about 30 dimmer stars being visible in addition to a dozen or so brighter members.
Hydra’s M48 is similar to M46 in that its stars have a fairly narrow range of brightness. It is somewhat brighter than M46, with an integrated magnitude of 5.8, but is not nearly as rich in my 8-inch. Still, not bad, not bad at all. What most novices will find challenging about this one is not looking at it, but looking for it.
If you don’t have goto or digital setting circles, the best bet is to use a half degree long line of three stars aligned northwest/southeast as a signpost. 1 Hydrae, C Hydrae, and 2 Hydrae are located 4-degrees 15’ northeast of Zeta Monocerotis, are in the magnitude 4.5 – 5.5 range, and stand out well in a finderscope. M48 is 3-degrees 15’ northwest of the three stars, and should show up without a hassle in a 50mm finder.
In the eyepiece, you’ll see a scattered, strongly elongated group of about 30 stars. It would be pretty ho-hum if not for the line of bright(er) members that crosses the center of the group. That line of stars, and a couple of arcs of suns also involved in the cluster at least make it somewhat interesting.
Now for something entirely different to end on, a Virgo galaxy, M49. It is bright and impressive for a galaxy, having a magnitude of 8.3 and a size of 10.0’, just right to be easily scarfed up by a 4-inch or even smaller telescope. No, there’s not a lot of detail to be seen, but it is a galaxy that is easy to run down from the backyard. The only problem is how to run it down.
M49 lies in the galaxy-rich wonderland, the “Realm of the Nebulae” between the arms of Virgo. The only saving grace here is that it lies well to the south of the densest area. There are numerous NGCs nearby but no adjacent bright Messier galaxies to confuse you. Still, it’s not easy the first time you undertake to navigate the Virgo Cluster with finderscope and chart. What I used to do before computers was “galaxy hop.” I’d use a wide-field Erfle or, later, a Nagler eyepiece, start at the Star Vindemiatrix, and literally hop from one galaxy to the next, using them as stepping stones to my destination.
When you are finally there, however you get there, don’t be too disappointed. What will be in the field is something that looks a lot like an unresolved globular cluster. A bright core and a hazy, round outer envelope. The better the sky, the bigger the envelope. This is a Hubble Type E2 galaxy, an elliptical galaxy, so there is simply not much detail beyond that to be seen. There are some nearby small 13th magnitude galaxies that can be visible in 12-inch and larger telescopes, and there are a couple of magnitude 13 range stars close by—nope, sorry, you have not discovered a supernova—but that is it.
And here we are approaching the halfway point in the list already. That is reason enough to put on the brakes. These objects are made to be savored. I won’t dash through them when writing about them, and you shouldn’t dash through them when viewing them, especially for the first time.