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Old 05-03-2008, 08:32 AM
你B
Its only a column of dust

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Quick Globular hunt

I need sleep but noooooooo I just had to force myself up at 2.30am, didn't I?
My mission was to see if I couod pick any details on NGC 3918 at very high powers. I checked the weather maps - all looked well, no jetstream, minimal high level winds and perfect calmness at ground level. Alas, the seeing was pure, absolute crap. Stars at the zenith were scintilating and those near the horizon were just messed up. It was yet another freezing cold Melbourne summer night.

Well seeing was trashed, so I figured I might try some of the bigger globular clusters.

Just a side note... I was browsing thru the Herald Bobroff atlas and found a section which shows distribution of various types of DSOs, and found that there's perhaps 5 times as many globulars on the southern side of the celstial EQ when compared to the north!

Had the sky atlas 2000 out with me, great for improptu sessions like this.

Scope: 10" GSO dob
Time: 3.45am-5.30am
Seeing: 4/10
Transparency: 4/5



NGC 6397
One of the several southern globulars that are apparently better than M13, it showed good resolution at 56x. At 192x the outer reaches appeared quite loosely bound, with a granular/hazy core. A circlet of several cluster members could be seen surrounding the core, with a red star among them. Increasing power to 250x bought out an additional 3-4 stars overlapping the core. Didn't expect to use such a magnification in light of the damn seeing.

NGC 6584
Smaller globular in Telescopium, east of Ara. At 56x it is a hazy orb and forms a neat triangle with two 7th mag stars. At 192x, about half a dozen stars were resolved, increasing power to 250x added a few more to the tally.

NGC 5286
Located just 4' NW of mag 4.7 M Centauri. Outer areas were well resolved at 250x, with some further stars superimposed across the granular core.

M4
Very easily resolved, even at 56x. Very nice at 192x. Doesn't have much of a condensed core although a bar which is unevenly populated by mag 11 stars crosses its center. A nice arc of 18 mag 11-13 stars "cradles" the cluster's western side.

NGC 6144
A faint ghost about 40' NW of Antares. A mag 12 star marks the W edge. At 192x I could resolve perhaps 10 faint cluster members.

M80
Still in the vicinity of Antares, NW of M4. Several stars across the outer half were resolved at 250x, with a bright condensed core.

NGC 6752
Apparently this is supposed to be the 4th best globular in the sky, am I correct? Located in Pavo almost midway between Peacock star and Ara. A mag of 192x bought out lovely arcs of bright stars streaming from the core, with a circlet of cluster members also present. The tight core showed granularity.

M22
Just a quick peek at 192x, now i see what all the fuss is about! Sorry northern Hemisphere, but you can keep your M13

Jupiter
Starting to look good! Maybe 6 bands resolved at 146x in moments of good seeing, some detail in both the NEB and SEB, with a wide rift in the SEB. A dark spot was seen in the EQ zone.
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  #2  
Old 05-03-2008, 08:52 AM
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erick (Eric)
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Thanks SAB for your report. Yes, I'm looking forward to M22 coming back into evening skies.
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Old 05-03-2008, 10:28 AM
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goober (Doug)
No obs, raising Harrison

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Quote:
Originally Posted by 你B View Post
It was yet another freezing cold Melbourne summer night.
Ah, there's your problem. It's autumn

Quote:
Just a side note... I was browsing thru the Herald Bobroff atlas...
Damn, you have a Herald-Bobroff? I've been trying to find one for six months.

Good report - we sure are blessed with great globs on this half of the world.
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Old 05-03-2008, 04:13 PM
你B
Its only a column of dust

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Quote:
Originally Posted by goober View Post
Ah, there's your problem. It's autumn
and its going to be warmer than February



Quote:
Damn, you have a Herald-Bobroff? I've been trying to find one for six months.

Good report - we sure are blessed with great globs on this half of the world.
We sure are Doug, we sure are. We are also blessed with the best examples of every other class of DSO aswell Doesn't it make you feel proud that the famous M42 and the Horsehead are also technically southern objects?

Really wet the appetite to do some serious globular hunting with my 12" light bucket That's in addition to our many fine galaxies and galaxy clusters. There's one disadvantage to living in the southern hemisphere - one life time is not enough

Another thing I've noticed - I aimed the 10 incher at the Homunculus nebula this morning, and was surprised by how much brighter it is in the 12". I also had a look at the trifid just as twilight was beginning - dark lanes clear as daylight

Quote:
Originally Posted by erick View Post
Thanks SAB for your report. Yes, I'm looking forward to M22 coming back into evening skies.
And with it come other goodies such as M5 and M10/M12. Scorpius/Sagitarrius also has a huge concentration of planetary nebulae, open the MSA on scorpius' tail and you'll find upto 5 PNs plotted in 1 square degree.

Last edited by 你B; 05-03-2008 at 04:28 PM.
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Old 05-03-2008, 11:31 PM
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ngcles
The Observologist

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Hi 你B,

Your observation of NGC 6379 piqued my attention immediately because you have noted something that, despite my asking far and wide for confirming observations, I thought I alone had ever seen -- the ring of stars around the centre.

In an old 1992 25cm observation I noted that ring, and then again in 1997. Then in 2002, I wrote an article for US S&T about "My Favourite Globulars" where I wrote:

"NGC 6397 in Ara is another very impressive naked-eye globular, though it doesn’t quite live up to the billing that one might expect given its proximity (it is probably the nearest globular to our Sun), its resolvability (it has the brightest individual stars of any globular), and its enormous halo (the third-largest). Its Shapley-Sawyer classification is IX, but in my opinion NGC 6397 seems more like a class XI cluster, with the large brightness differences between individual stars that are more typical of open clus-ters. Compare it to other globulars with similar brightness profiles — Omega Centauri, say, or M4 — and you will see that NGC 6397 stands apart.
One other unusual feature I have noted but never seen reported by others a nearly complete 3 arc-minute diameter ring of 11th-magnitude stars encircling NGC 6397’s geometric center. Within this circle very few if any stars are resolved. Has anyone else noted this?"

I am delighted at last that someone has also seen it!

Best,

Les D
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