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Dave Mitsky
Postmaster
Reged: 04/08/02
Posts: 6140
Loc: Pennsylvania, USA
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M4 is visible to the naked-eye from a dark site at an appropriate latitude.
Dave Mitsky
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Chance favors the prepared mind.
De gustibus non est disputandum.
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Dave Mitsky
Postmaster
Reged: 04/08/02
Posts: 6140
Loc: Pennsylvania, USA
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Quote:
But at higher magnifications, through telescopes, M4 resolves quite easily into individual stars. More easily than any other globular cluster, from my latitude of 42N. M22 is a close second.
M4 is much less rich than most of the great globulars, like M22, M5, or M13. Still , I would never describe M4 as being like an open cluster. The brighter stars are too similar in magnitude, so once you can see a dozen easily, there are a hundred more lurking at the edge of visibility. M4 may be sparse for a globular, but it's far richer than even superrich open clusters like NGC 7789. And in most conditions, the visible stars are set against a hazy nebulous background of unresolved stars.
That's an apt description of M4, which is one of the closest globulars to the Earth. If one absolutely has to compare the binocular view of this very loose class IX globular cluster to that of an open cluster, M11 might be a good match.
Through a telescope, a so-called "bar of stars" that runs through the cluster is readily apparent.
http://www.maa.clell.de/Messier/E/m004.html
http://apod.nasa.gov/apod/ap000523.html
Dave Mitsky
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Special Ed
Post Laureate
Reged: 05/18/03
Posts: 3479
Loc: Greenbrier Co., WV 38N, 80W
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Quote:
I would say M4 doesn't look anything like an open cluster. M4 is a very faint extended object more resembling a broad faint face on galaxy. It can be very difficult to see. very different looking than most all other globular clusters. M12 and M10 are condensed and bright by comparison. M3, M5 and M13 are extremely bright by comparison.
edz
Obx,
I think Edz makes an apt description here. Also as others have said in this thread, M4 is sensitive to light pollution and moonlight and to the observers latitude. One's expectations as to what the object should look like come into play as well. This sketch from latitude 38°N that I made not too long ago might help give you some idea what to expect when viewing M4 through binoculars.
I think M4 is a rewarding object to see no matter what instrument you use--I'm as awestruck that I can see this distant collection of stars whether it appears as a faint smudge through my binoculars or as a highly resolved and structured object as I recently viewed it through a friend's 16" Lightbridge. 
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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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Rich N
Post Laureate
Reged: 09/22/04
Posts: 5303
Loc: San Francisco Bay Area, Calif...
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Quote:
Quote:
M22 is an easier globular. M4 looks more like an open cluster.
Rich
I would say M4 doesn't look anything like an open cluster. M4 is a very faint extended object more resembling a broad faint face on galaxy. It can be very difficult to see. very different looking than most all other globular clusters. M12 and M10 are condensed and bright by comparison. M3, M5 and M13 are extremely bright by comparison.
edz
It may look more galaxy like in hand held binoculars. I usually don't pay much attention to it in binoculars.
Most of the time I'm looking at M4 with a 6" telescope. Through the 6" it doesn't seem to look much like a globular. Maybe it's because I'm using 50x to 75x.
Rich
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PhilH
sage
Reged: 01/27/05
Posts: 232
Loc: Long Island, NY
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Quote:
I think M4 is a rewarding object to see no matter what instrument you use--I'm as awestruck that I can see this distant collection of stars whether it appears as a faint smudge through my binoculars or as a highly resolved and structured object as I recently viewed it through a friend's 16" Lightbridge.
Very nice rendering of M4 and I agree with you completely. However, you and I (and many/most of the responders here) have been at this for years, even decades. We have trained our eyes to see the invisible -- beyond that, to see detail in the invisible! Obx isn't there yet, and as such is probably having a tough time understanding how we can say, as Dave did correctly, that M4 is actually visible to the unaided eye from a southerly latitude and dark skies.
Trust me, Obx, you'll also develop this ability to see the impossible, but it takes time. Have patience, stick with it and us, and before you know, you'll be seeing all sorts of sights that evade you now.
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Phil Harrington
"Binocular Universe" Columnist, Astronomy magazine
Author: Star Ware || Star Watch || Touring the Universe through Binoculars || et al...
http://www.philharrington.net
http://www.observingsites.com
"Two eyes are better than one!"
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12517
Loc: Cumberland, R I , USA42N71.4W
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Well said Phil.
edz
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
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Charles Laird
super member
Reged: 08/24/07
Posts: 109
Loc: Kerrville, Texas
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You might find it interesting to visit the Sketching forum here on Cloudy Nights. Look for posts under the title "Binocular Icon #.." by rodelaet. Rony has truely wonderful renderings using 8x56 binos and a special bino device which facilitates sketching.
He just published Binocular Icon #28 which is M4. Keep in mind though he is in a pretty good site. NELM is 6, and he is an experienced observer of small and very dim things.
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"Nothing is too wonderful to be true."
Michael Faraday
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milt
sage
Reged: 09/13/04
Posts: 424
Loc: Arizona
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Quote:
this very loose class IX globular cluster
Dave refers to the classification of globular clusters according to how concentrated their central stars are on a scale of 1 to 12 (first assigned by Shapely & Sawyer), with 1 being the highest central concentration and 12 being the lowest.
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Clear skies, Milt
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