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Inge
member

Reged: 08/17/12

The "third" globular in Hercules - a challenge new

#5416851 - 09/12/12 08:42 AM

The great globulars, M13 and M92 are all very well known objects. But Hercules also contains a third, more distant globular cluster. This is NGC6229, located in the north-western part of the constellation.
Detecting this globular is no challenge, not even with small telescopes. It is small and pretty bright. But because it is far away it isn't easy to resolve.

I can see some stars in it with my 12.5-inch from a normal dark site. Can anyone see stars with smaller aperture? Is it possible to partially resolve the cluster with 16 - 18-inch or larger scopes?

Post Extras:

Astrojensen
Post Laureate

Reged: 10/05/08

Loc: Bornholm, Denmark

Re: The "third" globular in Hercules - a challenge new

[Re: Inge]
#5417010 - 09/12/12 10:36 AM

While I've swept up NGC 6229 in a 13x50 binocular, I've never seen as much as a hint of resolution in any of my scopes (but I've not had my C8 on it yet either). It'll be a project for my new 12" LB.

I wonder how it looks in a 30"? There's going to be one at the star party I'm going to tomorrow!

Clear skies!
Thomas, Denmark

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blb
Post Laureate

Reged: 11/25/05

Loc: Piedmont NC

Re: The "third" globular in Hercules - a challenge new

[Re: Astrojensen]
#5417430 - 09/12/12 02:38 PM

The book "Star Clusters" by Archinal & Hynes lists the visual magnitude of the horizontal branch stars in this cluster as vmag. 18.0 This is the magnitude at which large numbers of stars start to become visible (i.e., the magnitude where the horizontal branch stars become visible) and, therefore, is an indication of the magnitude where the cluster will become "resolved out". On the best of nights from a realy dark site I can with high magnification see stars of magnitude 15.6+/-, so resolving this cluster with my 10-inch dob is out of the question. I don't know, can an 18-inch dob see mag. 18 stars? I think it will probably take a much larger telescope.

Post Extras:

rogerandgarf
sage

Reged: 06/01/05

Loc: Arlington, Wa

Re: The "third" globular in Hercules - a challenge new

[Re: blb]
#5417481 - 09/12/12 03:08 PM

Buddy,
If I were to use the Sky Commander limiting magnitude perameter on my 18" Starmaster as a guide, it maxes out at mag 17.

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Faith_J
Sketcher Extraordinaire

Reged: 11/17/04

Loc: South coast of England

Re: The "third" globular in Hercules - a challenge new

[Re: blb]
#5417483 - 09/12/12 03:09 PM

I observed this one years ago, with an 8 inch but I re-observed it back in May this year with my 18", using a 15mm Plossl (132x) on a fairly good evening.

'Compact with a bright core. Outer edges of the cluster are partly resolved with averted vision'.

Post Extras:

peter k
sage

Reged: 02/03/07

Re: The "third" globular in Hercules - a challenge new

[Re: blb]
#5417491 - 09/12/12 03:14 PM

Buddy, does the Archinal & Hynes book give horizontal branch magnitudes for most of the brighter GCs? I'm thinking of buying the book and if it provides that kind of info I'd be more inclined to pull the trigger. Thanks.

Post Extras:

blb
Post Laureate

Reged: 11/25/05

Loc: Piedmont NC

Re: The "third" globular in Hercules - a challenge new

[Re: peter k]
#5417525 - 09/12/12 03:36 PM

Quote:

Buddy, does the Archinal & Hynes book give horizontal branch magnitudes for most of the brighter GCs? I'm thinking of buying the book and if it provides that kind of info I'd be more inclined to pull the trigger. Thanks.

Yes it does for almost all the globular clusters and information like the Trumpler classification for most of the open clusters too. It's a great book.

Post Extras:

David Knisely
Postmaster

Reged: 04/19/04

Loc: southeastern Nebraska

Re: The "third" globular in Hercules - a challenge new

[Re: Inge]
#5417846 - 09/12/12 06:35 PM

Quote:

The great globulars, M13 and M92 are all very well known objects. But Hercules also contains a third, more distant globular cluster. This is NGC6229, located in the north-western part of the constellation.
Detecting this globular is no challenge, not even with small telescopes. It is small and pretty bright. But because it is far away it isn't easy to resolve.

I can see some stars in it with my 12.5-inch from a normal dark site. Can anyone see stars with smaller aperture? Is it possible to partially resolve the cluster with 16 - 18-inch or larger scopes?

The V-tip magnitude for NGC 6229 is 15.5 (represents the brightest few stars in the cluster) and the Horizontal Branch magnitude is 18.0, so while it can show maybe a few stars in a 12 inch, it doesn't resolve well in one. In my 14 inch f/4.6 Newtonian, my log entry for the cluster reads:

"Small faint fuzzy ball at low power. 188x hints at stars on the edges and 384x shows a number of very faint stars in the outer haze, but not well resolved. Cluster is still mostly hazy."

Clear skies to you.

Post Extras:

gnowellsct
Postmaster

Reged: 06/24/09

Re: The "third" globular in Hercules - a challenge new

[Re: David Knisely]
#5418429 - 09/13/12 12:30 AM

A fourth: Pal 14. GN

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KidOrion
professor emeritus

Reged: 07/07/07

Loc: Carbondale, IL

Re: The "third" globular in Hercules - a challenge new

[Re: blb]
#5418452 - 09/13/12 12:46 AM

Quote:

Quote:

Buddy, does the Archinal & Hynes book give horizontal branch magnitudes for most of the brighter GCs? I'm thinking of buying the book and if it provides that kind of info I'd be more inclined to pull the trigger. Thanks.

Yes it does for almost all the globular clusters and information like the Trumpler classification for most of the open clusters too. It's a great book.

Yeah, it is a great book.

The DSFG to U2000.0 also has the horizontal branch magnitudes in it, FWIW.

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george golitzin
Pooh-Bah

Reged: 02/24/06

Re: The "third" globular in Hercules - a challenge new

[Re: Inge]
#5418485 - 09/13/12 01:13 AM

Hi Inge--

From a very dark site (approx mag 7) in June, 2006, I have in my 16-inch f/5 the note "partially resolved."

From home (mag 5) 6 years later, I have in my 18-inch f/4.2 the note "hint of resolution around the edges, nothing definite."

Sorry I couldn't be clearer. But I think some significant resolution should be possible with an 18 on a dark and steady night.

-geo

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Inge
member

Reged: 08/17/12

Re: The "third" globular in Hercules - a challenge new

[Re: george golitzin]
#5418550 - 09/13/12 03:55 AM

There must be some stars brighter than 18th magnitude in this cluster. My experience is that I can see 15th magnitude stars with my telescope under dark conditions, so I believe NGC6229 has a few members that bright. The surrounding star field is sparse, and it is most unlikely that I just see foreground stars.

I read somewhere that the distance to the cluster is around 100.000 light years. A quick calculation gives me a distance modulus of 17,4. If the cluster contains stars with absolute magnitude between -2 and -3 they should be within my range. Checking the HR-diagram of M5 I find that this may be the case. Of course, the distance to NGC6229 may be uncertain, but the value I used somehow seems to make sense.
So, there is a chance of having a glimpse of some stars in a 12,5-inch, and certainly more stars with larger aperture.

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blb
Post Laureate

Reged: 11/25/05

Loc: Piedmont NC

Re: The "third" globular in Hercules - a challenge new

[Re: Inge]
#5418804 - 09/13/12 09:35 AM

Here is Steve Gottlieb's notes from the NGC/IC web site using an 17.5" telescope.

NGC 6229
16 46 58.8 +47 31 40
V = 9.4; Size 4.2'

17.5": bright, fairly small, very bright core, faint mottled halo. Roughly 10 extremely faint mag 15-16 stars are resolved around the edges of the halo at 280x. Forms an equilateral triangle with two mag 8 stars 6' W and 6' SW.- by Steve Gottlieb

Edited by blb (09/13/12 01:10 PM)

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blb
Post Laureate

Reged: 11/25/05

Loc: Piedmont NC

Re: The "third" globular in Hercules - a challenge new

[Re: blb]
#5418815 - 09/13/12 09:42 AM

Quote:

The book "Star Clusters" by Archinal & Hynes lists the visual magnitude of the horizontal branch stars in this cluster as vmag. 18.0 This is the magnitude at which large numbers of stars start to become visible (i.e., the magnitude where the horizontal branch stars become visible) and, therefore, is an indication of the magnitude where the cluster will become "resolved out"...

"resolved out" means fully resolved. Yes there are some stars that can be seen with a 12" to 18" scope but that's not fully resolved.

Post Extras:

uniondrone
Carpal Tunnel

Reged: 12/05/09

Loc: Streetlight Archipelago

Re: The "third" globular in Hercules - a challenge new

[Re: blb]
#5418892 - 09/13/12 10:31 AM

NGC 6229 is a fun object and an old favorite of mine, but I wouldn't consider it a challenge object. I view it routinely in a 10" dob from my white zone backyard. I find it to be an easier white zone object than probably about 80% of the Messier galaxies.

I glad that you recommend it, however. It seems to get overlooked a lot.

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EJN
Pooh-Bah

Reged: 11/01/05

Loc: Highway 61

Re: The "third" globular in Hercules - a challenge new

[Re: peter k]
#5419030 - 09/13/12 11:58 AM

Quote:

does the Archinal & Hynes book give horizontal branch magnitudes for most of the brighter GCs? I'm thinking of buying the book and if it provides that kind of info I'd be more inclined to pull the trigger.

Save some money.

Globular Cluster Data

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bassplayer142
professor emeritus

Reged: 10/03/11

Loc: Michigan

Re: The "third" globular in Hercules - a challenge new

[Re: EJN]
#5419061 - 09/13/12 12:13 PM

Pulled this last night with the 16" in red skies. Transparency was neh. All the way up to 313x I went but still couldn't resolve any individual stars. Though I did get that blotchy look I always attribute to Globulars.

Unfortunately my scope wasn't fully cooled, the wire just broke on my fan battery, and seeing was average. Maybe next time.

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blb
Post Laureate

Reged: 11/25/05

Loc: Piedmont NC

Re: The "third" globular in Hercules - a challenge new

[Re: EJN]
#5419161 - 09/13/12 01:06 PM

Quote:

Quote:

does the Archinal & Hynes book give horizontal branch magnitudes for most of the brighter GCs? I'm thinking of buying the book and if it provides that kind of info I'd be more inclined to pull the trigger.

Save some money.

Globular Cluster Data

It is still a great resourcee or reference that has data that is hard to find elsewhere. Still that is also a great refference to the NGC/IC web site.

Post Extras:

davidpitre
Post Laureate

Reged: 05/10/05

Loc: Central Texas

Re: The "third" globular in Hercules - a challenge new

[Re: EJN]
#5419890 - 09/13/12 08:24 PM

Quote:

Quote:

does the Archinal & Hynes book give horizontal branch magnitudes for most of the brighter GCs? I'm thinking of buying the book and if it provides that kind of info I'd be more inclined to pull the trigger.

Save some money.

Globular Cluster Data

I believe this is more up to date:
http://physwww.physics.mcmaster.ca/~harris/mwgc.dat

Post Extras:

EdK
member

Reged: 09/28/09

Re: The "third" globular in Hercules - a challenge [Re: davidpitre]
#5420733 - 09/14/12 10:56 AM

I have a number of images of NGC 6229 taken with my LX 90 12 inch and my Stellacam 3 camera, from my observatory here in Texas Hill Country. About a 6 second exposure.
It is rather bright and an impressive object.
Ed

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