Archive for the ‘Open cluster’ Category


Birthplace of suns

October 16, 2010

Normally I loathe just reblogging stuff from elsewhere on teh t00bz, but I make exceptions. Sometimes it’s nice to have your sense of wonder not just tickled, but smacked right across the room. This picture of NGC 346, from APOD, did it for me. Click through to the astronormous hi-rez version, and spend a few minutes zooming in and out. While doing so, try to hold these two ideas in your head at once: first, this is just one star-forming region in the Small Magellanic Cloud, which is a small satellite galaxy of the Milky Way, which is a big spiral galaxy in a small galaxy cluster on the outskirts of a not-terribly big supercluster, and so on and so forth; and second, every star in the picture is a sun, each with its own history and fate, most with their own systems of planets–and so on and so forth.

If NGC 346 was our entire universe, we could spend a thousand centuries exploring it and not exhaust its wonders. And yet you would not have to venture far into the closer galactic superclusters to find more galaxies than there are stars in the photo, each galaxy with more stars than you could count in a lifetime, each star with its own unique history.

Right! Enough of that! Back to fighting over our speck of dust.


The Moon and Pleiades, again

March 24, 2010

I wasn’t happy with the photo/sketch of the Moon passing the Pleiades that I showed in the last post. The field of view was too cramped to match what I saw at the eyepiece, and I put the stars in by flipping back and forth between Stellarium and GIMP and eyeballing things.

So this time I did it right: got a screenshot from Stellarium, pasted it into a layer in GIMP, placed the stars in a separate layer on top of that, and then got rid of the screenshot layer. Here’s the result, which is very close to what I actually saw Saturday night:

I liked the new version so much that I made a full-screen version. I don’t have any eyepieces that can actually show this much sky at once, but it looks pretty and I don’t care. Here it is:


Observing Report: A New High

March 21, 2010

Last night I was back down at the Salton Sea. I got down there right at sunset, found a spot in the Mecca Beach campground, and got the scope set up a little after 7:00. The sites on either side of me were empty but I had neighbors farther down the way and across the road that runs through the middle of camp. I walked around and invited people to come see the moon.

About eight people drifted in over the next hour or so, and most stayed for quite a while. We looked at the waxing crescent moon, Venus, Mars, the Great Nebula in Orion (M42), the Beehive (M44), M41 in Canis Major, and Mizar and Alcor. Saturn got up out of the near-horizon murk so we got a good look at the ringed planet and four of its moons. Mars showed a polar cap, some dark surface detail, and a possible cloud near the equator. Eventually we went on to galaxies–M81 and M82 in Ursa Major, which looked awesome in the same field of view, M55 and M56 in Leo (ditto), M51 and its satellite, and, most memorably for me, the Sombrero Galaxy (M104). The dark lane of dust that runs across the Sombrero was easy to see, and under those dark skies the galaxy showed a surprisingly extensive halo extending above and below the plane of the disc.

I’ve started working on the AL Caldwell Club so I spent some quality time on a couple of planetary nebulae, the Eskimo or Clown Face Nebula (NGC 2392) and the Ghost of Jupiter (NGC 3242). The Eskimo showed its prominent central star or ‘nose’, and in averted vision I could see some detail in the gaseous halo, but it was small and short on detail compared to the Ghost of Jupiter. The latter nebula was just awesome–it seemed about twice the diameter of the Eskimo, and there were definitely at least two concentric shells of gas around the central star, with the inner shell being brighter than the outer and clearly elongated out of round. Look at this image from about ten feet away and you’ll have a pretty good idea of what it looked like in the eyepiece.

I got a good look at Omega Centauri, the immense globular cluster that just gets over the southern horizon here. It was suffering from being down in the dense atmosphere near the horizon, but it was still a big ole ball of stars. At 92x, it looked as big or bigger in the eyepiece than M13, the Great Glob in Hercules, looked at 184x, and its stars looked smaller and more numerous. It is truly an outstanding object.

And speaking of M13, it was pretty darn good once  it got a good way up the eastern sky, with lots of resolution and long chains of stars emanating from the central ball.

It was  great night. As much fun as I had during the Messier Marathon last month, I had more fun last night just surfing around the sky and showing people cool stuff. I got better views of planetary nebulae, globular clusters, and galaxies than I have ever had from my own scopes. But the most amazing thing I saw all evening was, believe it or not, the moon.

I set up the telescope right before dark, tweaked the mirror alignment, and got the scope on the moon just by dead reckoning, without using the finder. The moon was exceedingly detailed and the entire globe stood out very clearly against the sky, which was not yet fully dark. And the moon was surrounded by stars, which was weird. Admittedly, it was still just a crescent moon, but between the glare from the moon and the evening twilight I didn’t expect to see any stars at all in the same field. They were there,  though. It occurred to me that the moon might be passing in front of a star cluster, as happens from time to time. Finally I got around to checking the finder scope and saw that the moon was cruising right past the Pleiades.

The view in a low-magnification eyepiece was indescribably beautiful, but I’ll try to describe it anyway. With the sky not fully dark, the razor-sharp moon seemed to hang suspended in front of a dark velvet blue sky, with the stars shining out like a halo of fireflies. The impression of depth was overwhelming–I could almost reach through the telescope and pluck the visibly spherical moon from among the streams of stars. Intellectually, I know the distances are all wrong–the velvety blue sky was in front of the moon, not behind it, and the stars were incomprehensibly more distant–but that’s what it felt like.

I took my best photo from last night and mocked up a very crude representation of what this looked like at the eyepiece. Imagine trying to tell someone about Michelangelo’s David when all you have to show them is a doodled stick figure and you’ll have a sense of what I’m up against. Nevertheless, here goes (image processing in GIMP, star positions from Stellarium):

UPDATE: I made a much improved, more realistic version of this image and put it in the next post.

So, I have a new favorite sport: catching the moon in front of star clusters during twilight. I’m sure it won’t happen that often, but the memory of just this first catch will last a lifetime. It was, hands down, the most incredible thing I have seen in any telescope of any size, anywhere, ever.

Best of all, it was accessible–anyone pointing even the most modest telescope skyward at the same time last night would have seen the same thing. So stay alert, you never know when the most seemingly ordinary of celestial objects will jump up and blow your mind.


Mission 19: Cross asterism near NGC 2281

March 4, 2010

Mission Objectives: Asterism, Open cluster

Equipment: Binoculars, Telescope

Required Time: 3 minutes

Related Missions: Diamonds from the Ring of Fire

An asterism is just a pattern of stars that grabs someone’s attention. Asterisms differ from constellations in that they don’t have any official standing, although some like the Big Dipper (which is only part of the constellation Ursa Major) are better known than their host constellations and have been recognized for far longer. Since asterisms don’t have to meet anyone’s standards for asterism-hood, anyone can point one out, and stargazers have been discovering them for as long as humans have watched the skies.

I noticed this one for the first time a few weeks ago when I was hunting down NGC 2281 with my 15×70 binoculars. It’s an easy catch–just find Capella, trace a line to Menkalinan the next star counter-clockwise in the ring of stars that marks the constellation Auriga, and extend the line an equal distance in the same direction. Might as well take in NGC 2281 while you’re there–it’s just southwest of the right arm of the cross.

NGC 2281 is a nice little open cluster for either telescopes or binoculars–another glittering diamond in the celestial Ring of Fire. But in this case, I like the asterism better than the cluster! It’s well worth seeking out, and definitely better in binoculars than in telescopes.

The cross asterism seems really obvious, but I haven’t found any other mentions of it so far. Does anyone know if it has been noted or discussed before? I’ll be grateful for any info.


Mission 18: Diamonds from the Ring of Fire

February 27, 2010

Mission Objectives: Bright stars, Open clusters, Messier objects, Star hopping

Equipment: Sky map, Binoculars, Telescope

Required Time: 5-10 minutes per window

Related Missions: Ring of Fire

Introduction: Here on Earth, diamonds are found in the magma pipes that fed long-extinct volcanoes. Sometime in the distant future, the volcanic provinces of the Pacific “Ring of Fire” will be prime diamond-hunting territory. So it’s fitting that winter’s Ring of Fire is also full of diamonds, in the form of open clusters that decorate the winter Milky Way.

All of the clusters described here are within reach of 50mm binoculars, although most won’t show much detail at 7-10x. Even the smaller ones will start to differentiate in 15×70 binoculars, and all of them are stunning in telescopes of any size.

Instructions for M41, M93, M46 and M47: Go outside after dark, face south, and find Sirius. Use it to trace the “doggy” shape of Canis Major. M41 is the biggest and brightest of the clusters in this area, and it’s an easy catch right in the heart of the dog. I usually find it by centering Sirius in the field of view and then just sweeping down (south) through the constellation. It never fails to swim into view. If you’re having a hard time, M41 makes one corner of an elongated triangle with Sirius and a trio of brightish stars along the dog’s back.

After M41, the rest of the Messier clusters around Canis Major may seem a bit anticlimactic, but each has its own charm and they are all well worth tracking down. And there are even better clusters to come.

Although it is nowhere near as brilliant as M41, M93 is one of my favorites. It is small but fairly dense, and at low magnification its irregular shape makes me think of a silvery flame burning in the night sky. To get there, trace your way down the dog’s back to the bright stars Wezen, Adhara, and Aludra, which mark the dog’s hindquarters and tail. If you’re in doubt about which is which, note that these three stars form a right triangle with Aludra at the south end. From Aludra, a loose chain of bright stars trails east into the constellation Puppis. Sweep over and up, over and up, and you’ll see M93. If you get to a star as bright as Aludra, you’ve hit Rho Puppis (looks like ‘p Pup’ in the map above) and gone too far.

The last two in this window, M46 and M47, make a nice contrasting pair. From Sirius, scan east to find the stars that make the back of the dog’s head. I imagine these stars forming one end of a shallow arc that includes several bright background stars and ends on the paired clusters. If that doesn’t work for you, use Stellarium or the atlas of your choice to pick out intermediate stars to use as waypoints. A word of caution: this is a rich region of the sky, with loads of tiny faint clusters that aren’t marked on any but the most detailed maps. More than once I have been looking for M46 and M47 and gotten hung up in the wrong place. If you have any doubt about whether the clusters you’re looking at are the right ones, they’re probably not. One way to recognize them for sure is to note the differences between them; M47 is very sparse with a handful of bright stars in an irregular pattern, whereas M46 has many more stars that are more even in brightness, although none of them are nearly as bright as the most prominent members of M47.

Instructions for M35-M38: Now go to the north end of the Ring of Fire, to the bright star Capella. Use it to trace the 5- or 6-sided (depending on how many stars you include) ring of the constellation Auriga. The side of the polygon opposite Capella is formed by the long line from Alnath (technically in the neighboring constellation Taurus) to the next star clockwise. The clusters M37 and M36 are on either side of that line at the halfway point. Extend the line from M37 to M36 on to the west with a slight bend to the north to find M38. As with M46 and M47, this trio of clusters make an interesting study in contrasts. Here are my notes from Messier Marathon night:

  • M37: compact, dense with faint stars, very rich but dim
  • M36: smallest but brightest of trio, dominated by a few brighter stars
  • M38: intermediate between the other two in both richness and brightness

The first time I observed these clusters, I found M37 and M36 easily and then spent almost an hour trying to locate M38. It just wasn’t there! Then I checked the descriptions of the clusters and realized that I had actually been looking at M36 and M38. I’d been extending the line in the wrong direction. I backtracked and picked up M37 easily–an illustration of why it is useful to know what things ought to look like, and not just where they are.

The Auriga trio are nice clusters, but the fourth and final M-cluster in this window blows them all away. To find M35, trace down the body of the western twin in Gemini, from bright Castor to the swooping arc of stars that marks the outside ‘foot’. Just above the toe of the boot, in a right triangle with the last two stars in the arc, you’ll find M35, a big, bright cluster that rivals M41 in either binoculars or telescopes. If you’ve got a telescope, you can get a twofer–the small, compact cluster NGC 2158 is right next to M35 in the same field. It’s a tough catch in binoculars unless you’re under dark skies, but almost any telescope ought to show it easily. There’s a nice photo of the pair here.

Instructions for M44: I saved the best for last. M44, also known as the Beehive Cluster or Praesepe (“the manger”), is probably the second best cluster in the sky after the Pleiades. But it’s not as easy to find. The Pleiades have enough bright stars to shine out even in suburban skies, but the Beehive is an aptly named swarm of smaller lights. To complicate matters, M44 is located in Cancer, which has no bright stars.

I usually get to the Beehive from Gemini. Here are some methods that might work for you. My usual path is to draw a line from the extended arm of the western twin, through Pollux, and on in the same direction for about the same distance. Right now that line also intersects Mars, so you could cut your travel time by just drawing a line from Pollux, through Mars, to Praesepe. But that method is only going to work for a few days, maybe a couple of weeks at most, because Mars is on the move (compare its position in the map above with this shot from just a few weeks ago). Finally, if your skies are really nasty, you might try drawing a triangle from Procyon, to Pollux, to Praesepe. It won’t be a perfect equilateral, but it’s close; M44 is just above the point of what would be a perfect equilateral.

Or you could do what I often resort to when I’m in  a rush: find the region between the Gemini twins and Regulus, in Leo (just off-screen to the lower left in the image above), and just sweep around with binoculars or your finder. It’s pretty low-fi, but it’s never failed me yet.

M44 is a true showpiece of the sky, with dozens of stars of even brightness seemingly arranged in a net or grid. It can be seen with the naked eye under dark skies, but it really shines in binoculars. As with the Pleiades, it usually looks better in binos than in telescopes, although a short focal length, rich-field scope might have a wide enough field to show the cluster with some surrounding sky for context.

Coda: The nine open clusters in this  mission are just the tip of the iceberg. This section of the winter sky is littered with hundreds more. There are plenty of bright NGC clusters that rival or exceed many Messiers. The region around the ‘feet’ of the Gemini twins is an especially rich area to sweep with binoculars or a telescope at low power, whether you’re hunting for specific targets or just soaking up the view.

Spring is coming. Although the constellations of winter are high overhead at sunset, they are already starting their long slide toward the western horizon. So get ’em while you can.


Collinder catalog PDF

February 16, 2010

Cloudy Nights has a great article about the Collinder Catalog, a list of 471 open clusters compiled by Swedish astronomer Per Arne Collinder for his 1931 dissertation. There have been requests in the forum to post the catalog as a PDF, so I copied the list and notes into OpenOffice (which is free, and awesome, btw) and exported it as a PDF. I would have simply posted the PDF to the Cloudy Nights forums, but they don’t allow attachments larger than 124 Kb. So I’m putting it here instead.

Please note that this is not my work at all; Thomas Watson did all of the heavy lifting in terms of updating Collinder’s list and turning it into a useful observing too. All I’ve done is convert it into a PDF so people can use it more easily.

Update, October 20, 2010: Thomas Watson posted an updated version of the catalog which corrects some minor errors in the first version. The v2 PDF below reflects those changes. Thanks for the heads up, Thomas–and for the mountain of work! It is certainly a lovely gift to the observing community.

The file:

Collinder Catalog v2


Observing report: Between the clouds

February 9, 2010

We’ve been having lots of cloudy and rainy weather here in the LA basin, so when a clear night comes along I try to take full advantage. Last night was clear, so I grabbed my 15x70s and went out to see the clusters between Cassiopeia and Perseus.

I made a New Year’s resolution to get through the Messier list this year. Right after I started on that project, I found out that some people–including Jay Reynolds Freeman–had done the whole list with 50mm binoculars. I hadn’t ever taken on a binocular observing project, so I decided to do the AL Binocular Messier Club at the same time. Plus, I would have felt like a wuss knowing that people had done the list with 50mm bins and I hadn’t even tried with my 15x70s. 🙂

The first week of January was pretty clear here and I got through almost all of the Messier objects that can be easily seen from my suburban skies at convenient hours. No M76 or M78 yet, at least not with the binoculars (M78 did fall to my 6-inch Dob). It was enough to get me hooked on the challenge and pleasure of tracking down faint fuzzies with binoculars, so I decided to start the Deep Sky Binocular Club, too.

I started that club a few weeks ago with what western objects I could get, before they get too close to the sun, or more depressing yet, too far down into the LA light dome (I’m at the far eastern edge of LA county). Then I went on through Orion, Lepus, Puppis, Gemini, Auriga, Taurus, and so on. A couple of weeks ago I was looking at my tally and realized that I’d gotten so busy with the southern stretches of the winter Milky Way that I’d forgotten about the circumpolar constellations! Which is a shame, Cassiopeia was the first constellation I learned when I got into amateur astronomy in earnest, and was a frequent stop on my earliest observing runs. And the stretch from Cassiopeia to Perseus is huge for the Deep Sky Binocular Club, with about a quarter of the objects on the list. I didn’t realize that until I’d gotten through most of the rest of the evening sky and was wondering why my tally wasn’t higher. Then I “discovered” how crucial Cass and Perseus are.

Then it started raining. A LOT.

As I compose this, it is raining. But last night was clear so I went cluster-hunting. I live in a back house with a big open parking area between it and the front house. This affords a decent bowl from which to observe without too much interference from local lighting. I usually wear a dark hooded sweatshirt and pull the hood up over my face so only my eyes are showing. With patience and good dark adaptation I’ve seen some things that I would have thought impossible in these skies, including the M galaxies around Canes Venatici and the Crab Nebula.

I didn’t start off with the Cass clusters. I wanted another crack at M78, and while I was waiting for my eyes to settle into observing mode I swept up M42 and M43, M35, and the Auriga M clusters. All very pretty, but they didn’t help M78 appear out of the murk. Sometimes right after a rain the transparency is just shocking, but sometimes there are mixed clouds and haze that really put the hurt on the faint fuzzies. Last night was one of those nights. M78 will have to wait for darker skies (maybe this weekend).

So I switched over to Cassiopeia and its neighbors. I started with the Double Cluster, which I’d seen umpteen times before but never logged for the Deep Sky Bino Club. And I was off and running. Here are the rest of my notes for the evening:

Tr 2 – Two chains of faint stars intersect to form the shape of a flying wing. Delicately beautiful.

Stock 2 – Extremely large, vase-shaped assemblage of faint stars. IMHO, rivals Double Cluster in binoculars, although its appearance is very different.

Markarian 6 – Dense patch of light, no granularity, makes a nice contrast with nearby Mel 15.

Melotte 15 – Larger and sparser than nearby Mark 6, but with more bright stars. Reminds me of a hybrid of the Double Cluster clusters.

NGC 663 – Obvious and granular even in these skies, brighter than nearby NGCs and even M103.

Kemble’s Cascade – Lovely curving chain of stars of varying brightnesses, anchored by NGC 1502 on one end and a counter-curving arc of bright stars on the other. Bright stars plus cascade make extended S shape.

Stock 23 – Jumps right out even in the surrounding rich starfield. Dominated by four bright stars in a flattened kite shape.

Cr 463 – Large aggregation of faint stars, smaller and dimmer than Stock 2, in a nice trapezoidal asterism not far from the pole.

All of these bizarre designations are explained in the official AL Deep Sky Bino Club list, and all of the listed objects are easy to find in the Pocket Sky Atlas.

I’d also tried for NGCs 129, 436, 457, and 7789, but didn’t pick them up. I think it was partly sky conditions–Cass was getting down into the LA murk–and partly observer conditions. I usually refuse to give up on something unless I have really put in the effort, maybe half an hour of laying flat on my back with every surrounding glint of light blocked out and lots of searching with averted vision. But last night I was cold and tired, and didn’t spend more than 4 or 5 minutes on any one thing.

Still, I ended the night with 10 more objects knocked off the Deep Sky Bino Club. The clouds can do whatever they want today, I’ve got a little victory energy to run on.


Mission 14: Three Astronomical Treats for Naked Eyes, Binoculars, and Telescopes

December 21, 2009

Mission Objectives: Bright Stars, Constellation, Open Cluster, Nebula

Equipment: Free star map, Naked eye, Binoculars, Telescope

Required Time: 10 minutes

Related Missions: Cassiopeia and the Double Cluster

Introduction: I’m in Oklahoma for the holidays. My best observation here so far didn’t require any optical aid at all. Remember last month when I was skunked in my quest to view the young crescent moon within 40 hours of new? On Thursday, December 17, the night after I got into town, I saw the 38-hour-old crescent moon in the western twilight over Oklahoma City, thus fulfilling the last requirement I had left for the Astronomical League‘s Lunar Club. I e-mailed in my completed log sheets on Saturday.

Instead of bringing a little scope with me, I borrowed back the one I had loaned to my brother. It’s a Synta MC90, another 90mm Maksutov-Cassegrain, but unlike my other little Mak it’s a short focal length, widefield scope. I got it out last night to show my nieces the waxing crescent moon, Jupiter, and the Pleiades.

Instructions: Speaking of the Pleiades (M45), they’re one of the best astronomical treats for a clear winter evening. Finding them is easy: look to the east after dark, and find a little knot of stars that looks a bit like a cooking pan. This is not the Little Dipper, although you’d be surprised at how many people think so on first spotting it. If you have a hard time finding the Pleiades, look for the 3/M/W of Cassiopeia, head past the Double Cluster to Perseus, and follow the lower of the two sweeping lines of stars that make up that constellation; the cluster is just off the end of the line. The Pleiades are pretty to the naked eye and probably best in binoculars. All but the widest-field scopes will have a hard time putting the whole cluster in the eyepiece, and even if you manage it, it’s prettier if you can see the cluster as a cluster, with a little open space around it. So this is one of those times that–in my opinion–binoculars trump a telescope.

If you have found the Pleiades, drop straight down (east) to find a V-shaped association of stars. These are the Hyades, another open cluster, in the constellation Taurus. One leg of the V is anchored by a big red giant star, Aldebaran, whose color is obvious even to the naked eye. You can pan around the Hyades with a scope if you like, but the cluster is so big that it really demands binoculars; binos fall right into the sweet spot of putting a lot more stars in your eyes without overly narrowing the view or getting you lost.

From the Pleiades, on to the Hyades, and farther on east you come to Orion, the most magnificent constellation in the sky. Find the three bright stars in a line that form his belt, and then three dimmer stars in another line that form the sword hanging from the belt. The middle of the three stars in the sword is not a single star at all. Rather it is M42,  the Great Nebula in Orion, a vast cloud of gas and dust, dozens of light years across, which is illuminated by the bright young stars burning within.

M42 is what I call a total object: like the moon, it looks good no matter what you use to look at it, and the more you look, the better it gets. With the naked eye, the nebula it is a faintly fuzzy star at the heart of a striking and majestic constellation. With binoculars, you’ll see a bit of nebulosity set amidst the rich starfields of Orion’s sword. In a small telescope, the full glory of the nebula starts to unfold, with glowing streamers of gas and dust spread out like an eagle’s wings. The central star will split apart into a group of four, called the Trapezium. Pour on more aperture and magnification and the view just keeps getting better. If the skies are clear and steady you may pick up a couple more stars in the Trapezium, and the surrounding clouds of gas and dust will start to look like clouds, with delicate knots and swirls.

And on it goes. You are not going to exhaust M42, not in a lifetime of observing. People with telescopes that require large trailers for transport, who have seen M42 literally thousands of times in their observing careers, still gaze into the heart of the nebula for minutes and even hours at a time. The bigger the scope, the darker the skies, the longer you look, the more there is to see.

But, hey, don’t think that if you don’t have a monster scope it’s not worth looking. Remember, M42 is a total object; it looks good at any scale. If the thought of setting up a scope in the cold and dark does not appeal, at least pop outside for a five minute session with binoculars. Make it a present to yourself.

Happy holidays!


Mission 11: Cassiopeia and the Double Cluster

November 21, 2009

Mission Objectives: Constellation, Open Cluster, Bright Star

Equipment: Naked eye, Binoculars, Telescope

Required Time: 3 minutes

Instructions: Go outside after dark, face northeast, and look for the sideways W. If you’re not sure which W is which, take a free sky map. The W is Cassiopeia, which lies right smack in the middle of the winter Milky Way.

Cassiopeia is a deep sky wonderland in binoculars and telescopes. There are more star clusters than you can shake a stick at–a decent portable sky atlas will show a dozen or more. Even without an atlas, it’s an awesome area to scan around in with optics of any size.

I have a confession, though. Almost every time I go out to observe in the winter, I give Cassiopeia a quick once-over and then leave. Why? Because there’s an even better pair of clusters lurking over the border of the neighboring constellation, Perseus, and Cassiopeia is such a good pointer that you might think it was put there for that purpose. Follow the inner leg of the shallow half of the W about 2/3 of the way to the next bright star, and you’ll find the Double Cluster, NGC 869 and 884. Keep in mind the effect of sky rotation–by 8:30 PM, Cassiopeia is an M centered over the North Star, and by midnight it’s a sigma to the northwest. Adjust your expectations accordingly.

The Double Cluster is one of the finest objects in the night sky, and almost always makes it onto lists with names like “Top 10 Telescopic Targets”. I’m not going to show you any pictures of the clusters themselves, because this is one place where pictures simply don’t do justice. You’ll have to get out under the night sky and see for yourself.

Once you’ve had your mind blown by the Double Cluster, keep on cruising in the same direction and follow the chain of bright stars to Mirphak, or Alpha Persei, the brightest star in the constellation Perseus. Mirphak is surrounded by a broad field of stars called the Alpha Persei association; it is too big to fit in the field of view of most telescopes (except possibly fast focal ratio, widefield scopes like the Astroscan and StarBlast 4.5), but is instead one of the best binocular targets in the entire sky. Have a look and let me know what you think.


Mission 7: Star clouds of Sagittarius

September 9, 2009

Mission Objectives: Globular Cluster, Open Cluster, Nebula

Equipment: Binoculars

Required Time: 5 minutes

Related Missions: Not Everyone’s Pot of Tea

Instructions: See how many deep space  objects you can see in Sagittarius with binoculars (or, if you must, a telescope). Here’s a guide:

Sagittarius again

Your job will be a lot easier if you’ve got dark skies. Here at the edge of LA County, M7, the Butterfly Cluster (M6), the Lagoon Nebula (M8), M21, M22, M24, and M25 are all fairly easy to spot with binoculars, and everything else is difficult to impossible. If don’t have dark skies and can’t get to any, at least get as much local darkness as possible. We have a little swath of lawn about 10 feet wide between the house and garage, and if I go back in there the buildings block out about half the sky, but the half they don’t obscure looks a lot darker because I can get all the local light sources (like the neighbors’ annoying security light) out of my eyes. Also, remember that pupil dilation just takes a few minutes, but full physiological dark adaptation takes an hour or so.

For my money the best thing in Sagittarius is the M24 star cloud. Go up from the lid of the ‘teapot’ to the first bright star (as indicated by one of the constellation lines in the image above). That star has a little curlique of followers trailing up and to the left. Follow to the curlique to the explosion of stars; that’s M24. It’s not really a cluster in the traditional sense. Rather, it’s a hole in the giant clouds of gas and dust that usually obscure the inner parts of the Milky Way from our view here in the galactic ‘burbs. According to Wikipedia, under optimum sky conditions (which I ain’t got) up to 1000 stars are visible through binoculars in M24. I can only see a few dozen, but it’s still pretty awesome.

Cheap bino mount

Finally, as always, the view through the binoculars will be a heck of a lot better if you can hold them steady. The best solution here is not to hold them at all, but rather to let a device hold the binos perfectly still while you just look through them. Most binoculars have a 1/4-20 socket at the front in between the objective lenses (this is usually covered by a small plastic cap and a lot of casual bino users don’t even know it’s there). You can use this socket to attach the binoculars to a monopod or tripod. Dedicated binocular tripod adapters are available online for a little as ten bucks, or you can build your own for about two. Get a small angle bracket or corner brace, a 1/4-20 wingnut to attach the bracket to the 1/4-20 bolt of the tripod (this is what you would normally screw the camera onto), and a 1/4-20 thumbscrew to attach the binos to the bracket, with maybe an extra wingnut to tighten things down.  BAM! Now you can aim and focus the binoculars, take your hands off and let the shaking settle down, and observe in shake-free comfort. It’s a qualitatively different experience from handheld binocular observing, and you will  see more.