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Berkeley 17 in Auriga
Dear Group,
The oldest (or second oldest) open star cluster in our galaxy is Berkeley 17 in Auriga with an estimated age of 10.06 billion years. Lying at a distance of 8,800 light-years away, the cluster is quite dim with a magnitude of only 14.0. NGC 6791 in Lyra has produced conflicting age estimates including a figure of 10.20 billion years. As a result, there is some ambiguity as to whether NGC 6791 or Berkeley 17 is the oldest cluster. Further details and a photo based on two hours total exposure is available at http://www.perseus.gr/Astro-DSO-Cluster-Berkeley-17.htm . Clicking on the image will yield an image with better image scale for viewing. In checking for other photos of Berkeley 17, I could only find one example taken using film emulsion. If anyone is aware of other sample images, I would be most interested. Clear skies! Anthony. |
#2
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Berkeley 17 in Auriga
On Mar 14, 7:38 pm, Anthony Ayiomamitis
wrote: Dear Group, The oldest (or second oldest) open star cluster in our galaxy is Berkeley 17 in Auriga with an estimated age of 10.06 billion years. Anthony, An exquisite image to say the least with round sharp points all across the field. Isn't it a real challenge to separate the true cluster members from the background star points? Your header declares that the brightest stars are only 16th magnitude. I think that is shortchanging this old fellow a bit and that figure ought to be revised upward to about 13th. Anyway I don't have any trouble seeing about 15 - 20 members with my 10 in. Great Work! Ben, 90.126 n 35.539 |
#3
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Berkeley 17 in Auriga
On Mar 14, 9:38 pm, Anthony Ayiomamitis
wrote: Dear Group, The oldest (or second oldest) open star cluster in our galaxy is Berkeley 17 in Auriga with an estimated age of 10.06 billion years. Lying at a distance of 8,800 light-years away, the cluster is quite dim with a magnitude of only 14.0. NGC 6791 in Lyra has produced conflicting age estimates including a figure of 10.20 billion years. As a result, there is some ambiguity as to whether NGC 6791 or Berkeley 17 is the oldest cluster. Further details and a photo based on two hours total exposure is available athttp://www.perseus.gr/Astro-DSO-Cluster-Berkeley-17.htm. Clicking on the image will yield an image with better image scale for viewing. In checking for other photos of Berkeley 17, I could only find one example taken using film emulsion. If anyone is aware of other sample images, I would be most interested. Clear skies! Anthony. Thanks for the beautiful Pic very professional. |
#4
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Berkeley 17 in Auriga
Your header declares that the brightest stars are only 16th magnitude. I think that is shortchanging this old fellow a bit and that figure ought to be revised upward to about 13th. Anyway I don't have any trouble seeing about 15 - 20 members with my 10 in. Great Work! Ben, 90.126 n 35.539 Oops! I just checked Uranometria's DSFG and they are in total agreement with you. This means I must have been looking at something else. Still a great image even if it is as difficult as 6791. Regards, Ben |
#5
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Berkeley 17 in Auriga
Ben wrote:
On Mar 14, 7:38 pm, Anthony Ayiomamitis wrote: Dear Group, The oldest (or second oldest) open star cluster in our galaxy is Berkeley 17 in Auriga with an estimated age of 10.06 billion years. Anthony, Hi Ben, An exquisite image to say the least with round sharp points all across the field. Isn't it a real challenge to separate the true cluster members from the background star points? The cluster and its minute member stars are much better visible with the larger image (when you click on the initial itself). Your header declares that the brightest stars are only 16th magnitude. I think that is shortchanging this old fellow a bit and that figure ought to be revised upward to about 13th. Not that I doubt you but can I please trouble you for a reference so that I can get a precise estimate and which I can also use in the future for forthcoming Berkeley clusters? My source ( http://messier45.com/cgi-bin/dsdb/ds...tr=berkeley+17 ) mentions mag 16.0 and in spite of the fact the cluster itself is stated as 14.0. Anyway I don't have any trouble seeing about 15 - 20 members with my 10 in. It is a real treat "seeing" so far into the past with this old cluster. We have predictions for good weather and high humidity this evening which should translate to good seeing. I will be going after M81, the stunning spiral in UMa, with six hours total exposure. Great Work! Glad you like the result! Anthony. Ben, 90.126 n 35.539 |
#6
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Berkeley 17 in Auriga
Ben wrote:
Your header declares that the brightest stars are only 16th magnitude. I think that is shortchanging this old fellow a bit and that figure ought to be revised upward to about 13th. Anyway I don't have any trouble seeing about 15 - 20 members with my 10 in. Great Work! Ben, 90.126 n 35.539 Oops! I am glad to see that my reference seems to be correct then. I just checked Uranometria's DSFG and they are in total agreement with you. This means I must have been looking at something else. I am already expecting the DSFG in the mail which will also help me in the future with such matters. Still a great image even if it is as difficult as 6791. Just a little patience for Lyra to get higher in the sky and we will have this one bagged as well. Anthony. Regards, Ben |
#7
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Berkeley 17 in Auriga
Not that I doubt you but can I please trouble you for a reference so that I can get a precise estimate and which I can also use in the future for forthcoming Berkeley clusters? Anthony, My source is Deep Sky Field Guide to Uranometria 2000.0 where on plate 97 it plainly saith: 05 20.6 + 30 36 Be 17 13'diam 100* 16mag photographic moderately rich, small brightness range, fairly even distribution, detached Which is a little disconcerting because it should have appeared as a proper little smudge like Tombaugh 5. But it didn't. That means I was seeing something else and Be 17 is going to be another tough object and I may not be able to see it at all. Ben |
#8
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Berkeley 17 in Auriga
Hi, Antony and Ben
Ben wrote: An exquisite image to say the least with round sharp points all across the field. Isn't it a real challenge to separate the true cluster members from the background star points? Antony wrote: The cluster and its minute member stars are much better visible with the larger image (when you click on the initial itself). I am happy to see that interesting objects such as open and globular cluster turn out, of some interest. However I must remember to Antony and Ben, that the only scientific procedure to select the true cluster members from field stars, is the knowledge of cluster reddening. Through reddening values we can obtain Vo = visual magnituides without reddening effects. Subsequently it will be possible - applying an empirical zams relation, like that of Schmidt-Kaler - to obtain the absolute magnitudes and the medium cluster distance modulus. An alternatively procedure, without any calculations, can be represented by the construction of a Color- Magnitude diagram that allows us to separate, graphically, cluster star members lying on zero age main sequence, from field stars. This second way, unfortunately, require science images through Johnson filters for instance. Regards, Valter. |
#9
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Berkeley 17 in Auriga
incredible when you think what went into discovering that mixed in with the
other stars. It's images like that that really force you to ponder the absurdity and wonder of it all. "Anthony Ayiomamitis" wrote in message ... Dear Group, The oldest (or second oldest) open star cluster in our galaxy is Berkeley 17 in Auriga with an estimated age of 10.06 billion years. Lying at a distance of 8,800 light-years away, the cluster is quite dim with a magnitude of only 14.0. NGC 6791 in Lyra has produced conflicting age estimates including a figure of 10.20 billion years. As a result, there is some ambiguity as to whether NGC 6791 or Berkeley 17 is the oldest cluster. Further details and a photo based on two hours total exposure is available at http://www.perseus.gr/Astro-DSO-Cluster-Berkeley-17.htm . Clicking on the image will yield an image with better image scale for viewing. In checking for other photos of Berkeley 17, I could only find one example taken using film emulsion. If anyone is aware of other sample images, I would be most interested. Clear skies! Anthony. |
#10
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Berkeley 17 in Auriga
Thanks for this good reminder!
Anthony Ayiomamitis wrote: Dear Group, The oldest (or second oldest) open star cluster in our galaxy is Berkeley 17 in Auriga with an estimated age of 10.06 billion years. Lying at a distance of 8,800 light-years away, the cluster is quite dim with a magnitude of only 14.0. NGC 6791 in Lyra has produced conflicting age estimates including a figure of 10.20 billion years. As a result, there is some ambiguity as to whether NGC 6791 or Berkeley 17 is the oldest cluster. Further details and a photo based on two hours total exposure is available at http://www.perseus.gr/Astro-DSO-Cluster-Berkeley-17.htm . Clicking on the image will yield an image with better image scale for viewing. In checking for other photos of Berkeley 17, I could only find one example taken using film emulsion. If anyone is aware of other sample images, I would be most interested. Clear skies! Anthony. |
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