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Open Clusters | |
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Berkley 58 Collinder 105 Czernik 5 Frolov 1 Harvard 21 IC 166 King 12 King 19 Trumpler 5 (Wide Field) Trumpler 5 Berkley 6 |
10-inch Newtonian, ST2000XM, 30:10:10:10 M52 is an open cluster with a diameter of 12.0', containing between 100 and 200 stars, depending of which study you want to rely on. The bright orange star on the right side of the cluster is not a member. The distance to this cluster is quite uncertain because it is heavily obscured by intervening dust. M52 is a fairly easy binocular object in clear dark skies. |
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10-inch Newtonian, ST2000XM, 30:10:10:10 NGC 6939 is an attractive but undistinguished open cluster. It contains about 80 stars in a diameter of 7.0' Almost all images posted of this cluster include it in a wide field image with the beautiful galaxy NGC 6946 (Arp 29), about 39' southwest.
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10-inch Newtonian, ST2000XM, 24:8:8:8 Messier 29 is a small (6.0' diameter), bright open cluster including about 50 stars. The eight brightest stars dominate the view and the numerous fainter stars seem to fade into the background. It is not very colorful. It lies behind a lot of dust, not seen in this image, and would be almost three magnitudes brighter if not dimmed by this dust. |
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10-inch Newtonian, ST2000XM, 20:7:7:7 NGC 6811 is a sparse open cluster located in the Cygnus Milky Way. It does not stand out strongly from the background. It consists of about 70 stars in a 12>0' diameter. The stars in, and around, the cluster are fairly colorful. While not an impressive cluster, this would be a wonderful target for a visual double star observer with a large scope. There are enough doubles and multiples to fill a night of observing. An 8-inch would be the minimum objective and a 12-inch or more would be even better, because most of the primaries are in the 11 to 13 magnitude range, with the companions as faint as 16 magnitude. |
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10-inch Newtonian, ST2000XM, 20:9:9:9 NGC 6885 is consists of 30 stars in a 18.0' diameter. That makes it a very sparse open cluster. The integrated magnitude is 8.1 -- the very bright star right in the center, 20 Vul, is not a cluster member. At magnitude 5.91, it is far brighter than the cluster. |
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10-inch Newtonian, ST2000XM, 30:10:10:10 NGC 2354 is a large (20' diameter) loose open cluster. It almost fills this field from top to bottom, as the field is 21.7' high. Megastar lists it as containing about 100 stars. There are many times that number in the center 20' of the image but it is in a region on the fringes of the Milky Way, so there are lots of foreground and background stars involved. Some faint, tiny galaxies can be seen through the cluster. I believe that the streaks in the background are reflections from delta Canis Major, about 1.5 degrees to the SW. |
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10-inch Newtonian, ST2000XM, 46:16:16:16 This is one of my favorite open clusters. It is a little below and slightly left of center, just below the triangle of brighter orange stars. Megastar credits it with 150 stars in a 12' diameter but I believe the number is well over 300. The generally yellow color is partially due to the age -- it is an old cluster -- but is more likely the result of viewing it through vast clouds of dust. The cluster is in (or behind) the nebula Sh2-273. The Christmas Tree Cluster and the Cone Nebula are part of this complex -- they are about a degree and a half away. The Christmas Tree is in a wide field image taken with my AT66 telescope and Trumpler 5 is included in that field. This image is far deeper. For a more delicate view, more like the visual impression in a very large telescope, click on the RGB button below. It also makes the nebulosity more obvious. |
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10-inch Newtonian, ST2000XM, 24:10:10:10 M36 is a bright open cluster in Auriga. It includes about 60 stars. Essentially all of the brighter ones are blue-white, B-type stars. It is one of the younger galactic clusters. There is nothing particularly interesting about this cluster, and my image is not at all outstanding, but I consider it one of the prettiest images I've taken. The mix of colors and brightness really catch the eye, and the network of diffraction spikes adds a special dimension. The Half Size image is the most attractive on my monitor, because it all fits on the screen.
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Astro-Tech AT66ED, ST2000XM, 60:20:20:20 minutes, 75' x 101' While M36 above is a very young cluster, M37 is a fairly old one. It shows a much wider range of star colors and lacks the concentration of young B-type stars. It has more than 150 members. But, since the diameter is almost twice as great as M36, the number of stars per square arc minute is actually less. The Half Size image is shown with my typical level of color saturation, and has a color balance that is close to "true color". I ramped up the saturation of the Full Size image to emphasize the deep red (garnet?) star very near the center of the cluster, and the intense blue stars which seem to be more concentrated in the outer fringes. Burnham refers to the red star as "a ruby on a field of diamonds" but I believe he is quoting an earlier observer. |
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10-inch Newtonian, ST2000XM, 48:12:12:12 NGC 206, located right in the center of the image, is the brightest star cloud in M31, the Andromeda Galaxy. Almost everyone has seen it in wide field views on the whole galaxy but it is not often targeted for imaging itself. You can see it in my wide field image on the Galaxies page -- it is fairly subtle. It is similar to M24 in our own galaxy, but is larger, brighter, and younger. There are about 32 globular clusters in this image. I have tracked down about a third of them but it is really not worth the trouble. Even the best look like stars that are a bit out of focus, and most can't be distinguished from nearby stars. Although I'm sure this feature is well known, I had never noticed that the arm closest to the W (upper-right) edge consists almost entirely of bright, very blue, stars.
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10-inch Newtonian, ST2000XM, 24:10:10:10 NGC 7510 is the brilliant open cluster near the left edge, while the sparse, faint cluster near the right edge is King 19. NGC 7510 includes about 60 stars within a 4' diameter while King 19 has 25 stars within a 6' diameter. It looks like 7510 is bleeding off the edge of the field, but it is not. The stars less than 2.5' from the edge are not considered part of the cluster. The structure of NGC 7510 is very unusual. To me, it looks like almost all of the stars are arranged into long, nearly parallel chains. It is a young cluster, with almost all of the stars being white. King 19 has the typical colors for an older, higher metallicity cluster. |
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10-inch Newtonian, ST2000XM, 24:10:10:10 NGC 7142 is an interesting object. It is one of the oldest open clusters and contains about 100 stars. Because of reddening by interstellar dust, the age and distance have been difficult to establish with any certainty. For an old cluster, it contains a surprising number of blue stars (mostly very faint) which are believed to be "blue stragglers". A number of these can be found by studying the full size image. They are among the faintest stars visible. At the same time, note the unusual number of background galaxies visible within, and just outside, the cluster. These are in no way connected to the cluster but I haven't encountered this many in other open cluster images, especially ones this short. Wikipedia contains a fairly extensive discussion of NGC 7142 at http://en.wikipedia.org/wiki/NGC_7142. |
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Astro-Tech AT66ED, ST2000XM, 40:(40 H-a):24:24:24 minutes, 101' x 74' This image contains six open clusters -- King 12, Harvard 21, Frolov 1, NGC 7788, NGC 7790, and Berkley 58 -- and one emission nebula -- Sh2-168. All of the clusters except Frolov 1 are on a nearly straight line starting with King 12 at the top right and ending with Berkley 58 near the left edge, about one-third of the field up from the bottom. Frolov 1 is left of the straight line, about 14' above and slightly to the left of NGC 7788. Originally, I had not properly identified it because the size listed in Megastar is much too small. Also, I had misidentified King 12 as Harvard 21 and had not spotted the real Harvard 21 at all. Neither Frolov 1 nor Harvard 21 are much to get excited about. My friend Dennis Webb came to my aid with some outstanding data mining, and got me on the right track. Sh2-168 is in the lower right corner. The image on the Half page has all of the objects marked and labeled, if you are having trouble finding them (like I did). The sizes of the circles approximately reflect the size of the objects but I did not make any effort to match them exactly, especially since a couple of them have no published diameters. This image was taken from my backyard in The Woodlands, TX. I took 40 minutes of H-alpha exposure, because Sh2-168 showed up very poorly in the luminance image, and blended it at a 15% level with the luminance. This had little effect on the stars and made Sh2-168 show up much better. |
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10-inch Newtonian, ST2000XM, 2:2:2:2 M73 is one of Messier's "mistakes". He correctly saw it as a tiny group of 4 stars but thought there was some nebulosity involved. Even the deepest modern images show no hint of nebulosity. I probably would never have bothered to image M73 except for a project by my astronomy club to do color images of all the Messier objects. You can see the result of our project at http://www.kellysky.net/jscas_messiers_draft_10x11.jpg. It is a large file and could take several minutes to load. And, while my images on this site are not copyrighted, this set of images is.
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Astro-Tech AT66ED, ST2000XM, 32:16:16:16 minutes, 67' x 101' M47 is a coarse open cluster including about 30 bright stars. Also shown are the tiny cluster NGC 2425 (also about 30 stars), near the bottom of the field, and the large loose group NGC 2423 (with 40 stars), at the top of the field. A little of 2423 is cut off at the edge. The RGB images were made at my home in The Woodlands, TX, and the luminosity was done at Fort McKavett, TX, during my club's spring star party. |
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10-inch Newtonian, ST2000XM, 28:16:16:16 This large, bright cluster is 21' in diameter and just fits within the field. It contains about 100 stars. It has a high concentration of blue stars and some yellow type G giants, giving it a pleasing contrast of colors. The brightest member, the yellow giant about halfway to the left side of the field, is magnitude 7.9. According to Burnham, "our Sun would appear as a star of magnitude 15.3 at the distance of M38". This is almost 1700 times fainter. |
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10-inch Newtonian, ST2000XM, 28:16:16:16 This bright, beautiful cluster contains about 80 stars. It appears to be concentrated toward the center of the field, but it actually fills the field from top to bottom and almost from side to side. Its diameter is listed at 22' and my field is only 21.7' in the short direction. |
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10-inch Newtonian, ST2000XM, 28:16:16:16 This image was made with the same scope, camera, and exposure time as M38 and M93, so they can be directly compared. While M50 appears larger than M93 and about the same size as M38, is is actually significantly smaller, only 16' in diameter. We are fooled by the area of brighter stars and tend not to notice the fainter outer members. M50 has about the same number of stars as M93 and slightly less than M38. It appears to have a lower percentage of yellow/orange stars than the other two clusters, being predominately blue or white. |
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Astro-Tech AT66ED, ST2000XM, 48:16:12:16 minutes, 76' x 100' M67 is a large, rich open cluster, containing about 500 stars in a diameter of 29'. It is unusual in a number of ways, being one of the oldest open clusters known and being located a large distance from the galactic plane. Open clusters are generally located in the plane of the Milky Way. This image was done at my home in The Woodlands, TX. |
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Astro-Tech AT66ED, ST2000XM, 16:16:16:16 minutes, 73' x 72' M41 is a bright beautiful cluster, 38' in diameter and containing about 80 stars. It is located about 4 degrees south of Sirius. This image had to be significantly cropped because it was shot over two nights, and I did not line it up properly the second night. It was made in The Woodlands. |
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Astro-Tech AT66ED, ST2000XM, 44:20:20:20, 75' x 101' This field has an open cluster for everyone! The large, bright cluster toward the lower right is NGC 663, the small, bright one in the upper right is NGC 654, and the much fainter, very yellow cluster near the top of the field about one-quarter of the way from the left edge is IC 166. IC 166 has the largest population, almost as many members as 663 and 654 combined, but is much more distant and dimmed by intervening dust. There are two more clusters that are hard to see in this thumbnail. Very near the left edge, about midway between top and bottom, is a tiny cluster of about 10 stars, Czernik 5. And midway between the left edge and NGC 663, about even with the south side of 663, is an irregular cluster of about 20 stars cataloged as Berkley 6. Most of the stars in Berk 6 form an irregular band running from NE to SW. Neither of these last two are easy to recognize as clusters. They seem to stand out best in the half size image. This image was taken in The Woodlands, TX |
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10-inch Newtonian, ST2000XM, 24:16:16:16 M103 is a bright but sparse open cluster in Cassiopeia. It only contains about 25 stars. It was the last entry in Messier's original catalog but several others have been added later. This is one of my poorer images. It was taken in bright moonlight. I was just looking for something I could image while I tried out a new separate guidescope arrangement. As you can see, neither the focus nor the guiding were good, and it is very noisy because of the moonlight. |
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 Christmas Tree Cluster (NGC 2264), Cone, SH2-273, and Trumpler 5 Astro-Tech AT66ED, ST2000XM, 60:32:28:28 minutes, 76' x 102' This is a beautiful and jam-packed field, and is my first image using the AT66 at my observatory. The bright nebulosity seen throughout the field is SH2-273. The Christmas Tree cluster is on the left, "upside down" in this N up presentation. The brightest star is the trunk and the little group at the other end is the "star" at the top. The Cone Nebula is at the bottom left of the field, just below the "star" on the tree. It is very small in this thumbnail and not large even in the full size image. It is an object that I need to image next year with my 10-inch. Trumpler 5, in the lower right, is a spectacular open cluster, strongly reddened (or yellowed?) by the dust clouds in our line of sight. It is one of the most impressive of all open clusters. There are many dark nebula in the field but the only one that I can find a catalog designation for is B39, right at the top center. |
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Astro-Tech AT66ED, ST2000XM, 30:24:20:20 minutes, 76' x 102' The Beehive is a young, sparse, very blue open cluster. It is a delightful binocular object in the center of Cancer but not a very exciting imaging target. This image was acquired at my home in The Woodlands, TX, where light pollution makes anything but open clusters difficult. |
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Astro-Tech AT66ED, ST2000XM, 20:16:14:10 minutes, 76' x 102' This very pretty open cluster in Puppis was imaged the night after M44, above. The exposures were cut a little short because I could see I was heading to the trees and, in fact, my last two blue exposures were lost because of this. I usually shoot equal exposures in green and blue, with about 25% more in red, based on the G2V calibration for my camera. One of the "missing" NGC objects, NGC 2542, was recorded just a few arc seconds from 19 Puppis, the bright star at SE edge of NGC 2539. It is probably missing because of an error in the initial recording of it's position. This object was imaged from The Woodlands, TX. |
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Astro-Tech AT66ED, ST2000XM, 24:20:16:16 minutes, 76' x 102' The large, rich, blue open cluster is M46 (NGC 2437),and the tiny planetary is NGC 2438. NGC 2438 is very nearly a twin of the Ring Nebula, but much smaller. While it appears to be part of the cluster, it is now thought to be just a chance alignment. I find the percentage of blue stars within the cluster compared to the percentage outside the cluster to be striking. With NGC 2438 and the very orange bright star SW of the cluster, it is a colorful and beautiful field. This is another image from my observatory in West Point, TX. |
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Astro-Tech AT66ED, ST2000XM, 44:28:24:24 minutes, 76' x 102' Messier 35 is the large, young open cluster at the center of the field. NGC 2158 is the much smaller cluster to the SW. It has almost five times as many members as M35 but is about six times more distant. The yellow color is probably partially due to the age -- it is a much older cluster than M35 -- and partially the result of absorption by intervening dust. Together, they make a beautiful pairing. My telescope is not a true ED, as you can see from the halos around the brighter blue stars, but it still provides a pretty decent image. |
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Astro-Tech AT66ED, ST2000XM, 16:16:16:16 minutes, 76' x 102' This very young, very blue, cluster occupies the center 54' of the field but does not really stand out. Somewhat surprisingly, it is much more obvious in my 9 x 50 finder than in the image. The image includes a huge number of background stars that are below the magnitude visible in the finder. To me, the most interesting things about this cluster are a horseshoe shaped collection of stars with the closed end at the center of the field and opening to the lower left (SE), and several long chains of stars just above the cluster that look almost like writing. |
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 Double Cluster (NGC 869 & 864) Astro-Tech AT66ED, ST2000XM, 30:16:16:16 minutes, 76' x102' This is an image made from my backyard in The Woodlands, TX. Open clusters are about the only deep sky objects which can be easily be imaged with the light pollution, except for bright and planetary nebulae using narrowband filters. The Double Cluster is a beautiful object visually, even with binoculars or a small telescope. In dark skies, it can be found fairly easily with the naked eye. This is a replacement image which improves on the previous version by having triple the exposure time, 1x1 binning, and no Moon lighting up the scene. |
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Astro-Tech AT66ED, ST2000XM, 10:10:10:10 minutes, 76' x102' NGC 1746 is smaller and denser than NGC 752 below, and appears even richer because it is seen against a background of stars on the fringes of the Milky Way. |
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Astro-Tech AT66ED, ST2000XM, 10:10:10:10 minutes, 76' x102' NGC 752 is a very large, very sparse open cluster but the stars show some attractive color contrasts. There are probably about 65-70 members. While it is not often imaged and not very impressive either in an image or at the eyepiece, it is an interesting cluster with a lot of astrophysical work done on it. Burnham devotes four full pages to this object. |
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Astro-Tech AT66ED, ST2000XM, 20:12:10:10 minutes, 76' x 102' Messier 34 is a moderately large, loose open cluster in Perseus. The blue giant stars really dominate this cluster.
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