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rodelaet
Post Laureate
Reged: 04/28/06
Posts: 3063
Loc: 50°56' N - 4°58' E (Belgium)
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M7 is, with a declination of -35°, the most southern Messier object. From my backyard, M7 never raises higher then 4.5° above the horizon. I was fortunate to observe this beautiful open cluster from dark observing site during a summer vacation in Spain. M7 and M6 were visible to the naked eye as two brightenings along the Milky Way near the Sting of the Scorpion. M7 was the most obvious, while M6 needed a keen eye to be detected. These two galactic gems were known even before written history. The name that the Arabs gave to these two clusters : ‘The Venom of the Scorpion’, always triggers my imagination.
M7 can not be missed, even when it’s not visible with the naked eye. The beautiful cluster can be found about 4° north-east of Lambda Scorpii. M7 appears very large, with fifteen bright stars scattered over an area of 80’. A bright double star can be seen near the center of the cluster. With averted vision, the number of cluster members can grow to over 50, depending on the size of the used binoculars. The majestic splendor of M7 is best appreciated with small to medium binoculars. This cluster is simply too large for common telescopes. M7 is 800 l-y away and has an integrated magnitude of 3.3.
Note : the initial sketch was created with a resolution of 1600x1600 pixels. Because of the forums restriction, the sketch is resampled to 800x800. This resolution is far inferior to the level of resolution that the human eye is capable of behind the eyepiece. As a result, close (but clearly separated) doubles, like the one in the center of this cluster, risk to become smeared out on the low resolution sketch.
Site : Andratx, Mallorca, Spain ( 39° N )
Date : July 27, 2008
Time : around 22.00UT
Binoculars : TS 15x70 Marine
FOV: 4.4°
Filter : none
Mount : Trico Machine Sky Window
Seeing : 2/5 (the view suffered from heavy turbulences in the air)
Transp. : 4/5
Sky brightness : 21.08 magnitudes per square arc second near zenith (SQM reading).
Nelm : 6.5
Sketch Orientation : N up, W right.
Digital sketch made with Photo Paint, based on a raw pencil sketch.
(Note: if the sketch does look too dark on your monitor, try to darken the room.)
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Rony
My Astronomical Sketches
My Binocular Sketches
Callibrate your Monitor with this little strip.
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rolandlinda3
Carpal Tunnel
Reged: 01/24/06
Posts: 2233
Loc: Crozet VA 22932
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Rony, you make me hungry to get back on the Sky Window. Roland
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Roland
Sketches in members galleries: rolandlinda3
Inspirational stories/sketches at:
www.christworksministries.org
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rodelaet
Post Laureate
Reged: 04/28/06
Posts: 3063
Loc: 50°56' N - 4°58' E (Belgium)
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Thanks, Roland!
Which makes me wonder : how are the bino's and the Sky Window doing in your presence?
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Rony
My Astronomical Sketches
My Binocular Sketches
Callibrate your Monitor with this little strip.
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frank5817
Post Laureate
Reged: 06/13/06
Posts: 4084
Loc: Illinois
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Rony,
I was certain that if you captured M-6 you may also have sketched M-7. Wow.  I am glad you did. Beautiful sketch and report of M-7.  I would have guessed that M-7 was not visible from Belgium. 4.5 degrees above the horizon is a difficult target. You need to get away to Spain more often- good friend.  
Frank
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my gallery
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GlennLeDrew
Pooh-Bah
Reged: 06/18/08
Posts: 1250
Loc: Ottawa, Ontario, Canada
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Rony,
If you wish to preserve detail in a posted image, how about cropping away the outer bits, and keeping the central 800x800 portion of interest?
Nice renderings of this and M6!
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Home-made 11X50 right angle bino, 8.1 deg. FOV
Modified 26X100 bino, 3.5 deg. FOV
Home-made Mk II RA bino, using interchangeable objectives and eyepieces
My Gallery
Mediocre minds discuss people. Good minds discuss events. Great minds discuss ideas.
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CarlosEH
Post Laureate
Reged: 01/19/05
Posts: 4132
Loc: Pembroke Pines, Broward County...
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Rony,
A spectacular observation of one of my favorite open clusters and deep sky objects. You have captured the sparkle of this cluster very nicely in your observation. Thank you for sharing it with us all.
Carlos
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rodelaet
Post Laureate
Reged: 04/28/06
Posts: 3063
Loc: 50°56' N - 4°58' E (Belgium)
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Frank, Glenn and Carlos,
Your comments are much appreciated!
Glenn, Thanks for pointing me to a solution. I can crop the image and use it as an insert in one of the corners of the sketch.
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Rony
My Astronomical Sketches
My Binocular Sketches
Callibrate your Monitor with this little strip.
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Special Ed
Post Laureate
Reged: 05/18/03
Posts: 4287
Loc: Greenbrier Co., WV 38N, 80W
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Rony,
Beautiful work and a nice complement to Carlos's telescopic view.
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Michael Rosolina
8" f/10 Orange Tube SCT
4.25" f/4.2 Astroscan Reflector
SVP 3.6" f/13.6 CA Reflector
40mm PST f/10
APM Germany HD 15x70 binoculars
Canon 12x36 IS II binoculars
Mark I Eyeball
My CN Gallery
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rodelaet
Post Laureate
Reged: 04/28/06
Posts: 3063
Loc: 50°56' N - 4°58' E (Belgium)
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Thank you, Michael.
It is indeed a nice comparison with Carlos's sketch.
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Rony
My Astronomical Sketches
My Binocular Sketches
Callibrate your Monitor with this little strip.
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