#1  
Old 28-04-2011, 11:28 AM
Rob_K
Registered User

Rob_K is offline
 
Join Date: Oct 2006
Location: Bright, Vic, Australia
Posts: 2,101
Rup 106 & E3

Continuing the quest for ever-more impossible globular clusters in a cheap 4.5" scope...

Anyway, last night we had our monthly club observing night out at the Porepunkah airstrip, and were greeted with great skies. Tons to see, cruised all the biggies, some fantastic views.

I came prepared with charts for globular clusters Rup 106 and E3, both well-positioned. Try as I might, I couldn't get a hint of anything at the E3 position, no surprise there.

Rup 106 was a different matter, and I'd like to get some advice on this from people who might have seen it before. Because it seemed relatively easy to me (compared to some impossibly faint things I have chased down LOL). I first looked when there was still a hint of brightness in the sky (just to nail down the position) and there was nothing there. A bit later, in dark sky, a very faint background glow was visible in the position, perhaps 4 arcminutes in diameter. I could hold it quite well, knocking the eyepiece and moving the field with the hand control. It never quite assumed a proper form, bits of it flickering in and out. Conditions were excellent - two mag 6.4 stars close to it were easy naked-eye. I checked the position again later as mist was starting to rise and there was nothing there again - amazing the effect of a bit of moisture in the air.

I've attached a rough sketch of what I was seeing - the 'glow' I've drawn is considerably exaggerated of course, it was a ghost of a ghost! In hindsight, I should have 'commandeered' one of the bigger scopes on the field to check it out, but I'm that used to observing on my own it didn't occur to me.

Comments, advice welcome!

Cheers -
Attached Thumbnails
Click for full-size image (Rup 106 sm.jpg)
85.8 KB18 views

Last edited by Rob_K; 28-04-2011 at 12:05 PM.
Reply With Quote
  #2  
Old 28-04-2011, 02:53 PM
Paddy's Avatar
Paddy (Patrick)
Canis Minor

Paddy is offline
 
Join Date: Jun 2007
Location: Strangways, Vic
Posts: 2,208
Nice one Rob. I've not looked for this one before but your sketch matches what it looks like on Wikisky perfectly. If I get some observing in tonight I'll have a go.

What does E stand for? Might have a go at that one too.

As always, impressive what you achieve with the Tasco 4.5! I dips me lid.
Reply With Quote
  #3  
Old 28-04-2011, 03:19 PM
Rob_K
Registered User

Rob_K is offline
 
Join Date: Oct 2006
Location: Bright, Vic, Australia
Posts: 2,101
Thanks Patrick!

Quote:
Originally Posted by Paddy View Post

What does E stand for? Might have a go at that one too.
E3 (ESO 037-SC001 = C0921-770) was one of three star clusters found on ESO blue plates in 1976, so I presume the E stands for "ESO". E2 was an open cluster (in the LMC halo), while E1 & E3 were globular clusters. But E1 was later found to be identical with globular cluster AM1.

E3 should be well-gettable with your scope. It's nominally vis mag 11.4, but it's large and very diffuse. Good luck - post a report!!

Cheers -
Reply With Quote
  #4  
Old 28-04-2011, 04:14 PM
Rob_K
Registered User

Rob_K is offline
 
Join Date: Oct 2006
Location: Bright, Vic, Australia
Posts: 2,101
Oops, I should have added that this isn't the first time I've tried for Rup 106 in the 4.5". First time there was nothing there, but in 2008 in pretty good conditions (but not as good as last night) I had tantalising glimpses of "something" but nowhere near enough to convince me that I had seen it. Strange how time gets away and it's three years later before I try again!

Cheers -
Reply With Quote
  #5  
Old 29-04-2011, 12:08 AM
pgc hunter's Avatar
pgc hunter
Registered User

pgc hunter is offline
 
Join Date: Feb 2009
Location: Renmark, SA
Posts: 2,939
Well done Rob. You've certainly milked that Tasco to no end Try using a dark shroud over your head when hunting such faint objects. I find it helps alot.

Last edited by pgc hunter; 29-04-2011 at 12:33 AM.
Reply With Quote
  #6  
Old 29-04-2011, 09:45 AM
Rob_K
Registered User

Rob_K is offline
 
Join Date: Oct 2006
Location: Bright, Vic, Australia
Posts: 2,101
Thanks pgc! Well, someone did hunt up a report of Rup 106 observed through a 110mm x 805mm newt - similar observation to mine except that I appear to have seen more of it. Just need those 'magic' dark nights, bit like the legendary 'perfect seeing' nights! Pretty comfortable adding it to my MW globular cluster list now. 105 & still counting!

Cheers -
Reply With Quote
  #7  
Old 29-04-2011, 12:34 PM
pgc hunter's Avatar
pgc hunter
Registered User

pgc hunter is offline
 
Join Date: Feb 2009
Location: Renmark, SA
Posts: 2,939
Quote:
Originally Posted by Rob_K View Post
Thanks pgc! Well, someone did hunt up a report of Rup 106 observed through a 110mm x 805mm newt - similar observation to mine except that I appear to have seen more of it. Just need those 'magic' dark nights, bit like the legendary 'perfect seeing' nights! Pretty comfortable adding it to my MW globular cluster list now. 105 & still counting!

Cheers -
I'm a firm believer in the ability of an observer to see difficult/extremely faint objects through relatively modest apertures, the difference is you gotta know what you're doing and how to make the most of the scope and conditions

Legendary seeing eh...as far as Melbourne is concerned this failure of a season, the ability to resolve stars into pinpoints at anything above 100x is to be considered legendary

Last edited by pgc hunter; 29-04-2011 at 12:46 PM.
Reply With Quote
  #8  
Old 30-04-2011, 12:01 PM
Brian W's Avatar
Brian W (Brian)
The Wanderer

Brian W is offline
 
Join Date: Jan 2008
Location: Dumaguete Philippines
Posts: 757
Rob, I thought I was a minimalist using an 8". I may just have to dig out the 4.5 again.
Brian
Reply With Quote
  #9  
Old 11-05-2011, 10:30 AM
ngcles's Avatar
ngcles
The Observologist

ngcles is offline
 
Join Date: Dec 2006
Location: Billimari, NSW Central West
Posts: 1,571
Hi Rob,

Yep the sketch shows a good position for Ruprecht 106 and I think it would be barely visible in 10.5cm given top quality skies and moderate magnification. I didn't find it hard at all in 25cm and here's my note from Bargo in 1996:

x86 34' TF. x171 17' TF. Not a particularly difficult object. Found in a field of nearly innumerable *s, 2 deg S of Gamma Centauri. Appears as an unresolved fairly sizable milky glow perhaps 2.5' diameter. Seems to have several faint superimposition *s about mag 14. Mag 9 * to the S by 3'. Scattered mag 13-14 *s like the sands of the beach.

The V-tip magnitude (brightest AGB member stars) for Ru106 is given as 14.8 so it isn't out of the question that some of the stars I saw were actual resolved member stars

E3 is a somewhat different bucket of fish. It is a very faint object for 30cm class 'scopes and still not particularly straightforward in larger ones.

I happened to look in on both last weekend up at Mudgee. Ru106 appears partly resolved in 46cm with maybe a dozen faint stars in the mags 14.5-16 range scattered over its LSB face that appears about 2.5 arc-mins across.

E3 even under a sky with an SQM-L reading of 21.55 was a sizable faint blur approaching 3.5 across that looked a little patchy or perhaps grainy but not resolved. In 50cm it appears to have raggedy edges.

Both show little to no concentration to centre.

Hope this helps.


Best,

Les D
Reply With Quote
  #10  
Old 11-05-2011, 11:33 AM
Rob_K
Registered User

Rob_K is offline
 
Join Date: Oct 2006
Location: Bright, Vic, Australia
Posts: 2,101
Thanks Les, greatly appreciated! Yes, I didn't have any real expectation of seeing E3. I would still like to have another go at Rup 106 under the very best skies - just a tiny niggle that I seemed to see more than what is actually there. I'll also 'commandeer' a bigger scope if I can to double-check. Need some 'drought skies' - there's still so much moisture in the air that it has to affect observation, even when skies are dark.

There's still a couple more very faint globulars on my list, not presently well-situated for viewing...

Cheers -
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 07:16 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
NexDome Observatories
Advertisement
Celestron Australia
Advertisement
OzScopes Authorised Dealer
Advertisement
Meade Australia
Advertisement
Bintel
Advertisement
Lunatico Astronomical
Advertisement
SkyWatcher Australia
Advertisement
Astronomy and Electronics Centre
Advertisement