M7, Ptolemy's Cluster--Click here to see the larger version
Registar finds 41,956 stars in this frame. Whoa! I'd hate to try to count those by hand...
Image Details: 8x4 minute exposures on 3/25/2006 at HAS site near Columbus, TX, USA. Canon EOS 20Da (unmodified), Takahashi TOA 130 (a 5" APO refractor), Losmandy G-11 mount. My current image processing workflow is here.
Messier object number 7 (Ptolemy's Cluster) is one of the best binocular clusters in the sky. It's at the tail of Scorpius the scorpion. You can see the backdrop of the Milky Way, along with various dark nebulae in the area. This star is on a line of sight to one of the brightest areas of our Milky Way Galaxy. When you look in this direction you are looking toward the center of the galaxy.
This is the southern-most object in Charles Messier's Catalog. There are some clusters just below this that Messier was unable to view from Paris; M7 was just a few degrees above the horizon there at its highest. See some nearby objects on my 3/25/06 Southern Spring Skies from Texas page.
The table below shows some of my previous efforts at M7.
 M7, Open Cluster Near Scorpius (old version) | Left image from 2004 taken in the Davis Mountains, Texas. Dark Nebulae are visible: B287 just to the left of the middle cluster, B283 is to the right and down from the cluster, and perhaps B87 on the mid-upper-right part of the picture. | Another M7 here. |
 1200 pixel wide version of M7, Open Cluster |
|  M7 Picture, Full Frame (GradientXTerminator used) |
 M7 Picture, Full Frame (GradientXTerminator used) 300 mm |  M7 Picture - Saturated Version - still another version! |  M7 - Prime Focus Just before Midnight, 5/30/2005, Wimberly Texas. Compare this "through the 'scope" version with the other, wider-field, images. This image is much narrower, with an effective frame size of a 1130mm lens considering the 1.5x magnification factor of my Nikon D100 Digital SLR (D-SLR) camera. Takahashi TOA 130 (5" APO refractor) With reducer, focal length is 754mm at f5.8 |
Processing Notes, 5/22/05: I've had a lot of fun working with this image in Photoshop. I'm still not happy with it.. This version postulates that the brightest part of the milky way, in the center, should be approximately white. I blended in a "flat" from another shot with the same lens to address vignetting. Still a slight trend towards purple here and there. I also did some Photoshop Advanced channel blending. (Blended some blue into green channel, among other things.
Photo info: Nikon SLR Camera, Nikon 300mm F2.8 ED lens at F2.8; around 15 minutes exposure on Kodak LE400 film, Losmandy G11 mount.
Images and text Copyright © 2005, 2006 Dick Locke. All Rights Reserved.
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