Shakhbazian 122 and 123 in UMa

[Martin Meredith]

Shakhbazian 122 and 123 are a pair of very faint compact groups of galaxies lying in the middle of the bowl of the big dipper (or the back of the great bear if you prefer).

SHK 123 is the brighter of the two, with a most prominent member of mag 17.7. Its 11 galaxies form an almost perfect north-facing 'u' shape. All of them are visible in a 2x30s capture, but the view improves with time to allow the ellipticism of some members to appear. Here's a shot showing a mean stack of 13 subs, complete with a zoom and an identification chart. 

The chart indicates general agreement on a distance of 1.75 billion LYs, and it therefore seems that the 3 satellites to the SE are also part of the physical group. Interestingly, the galaxy to the SW is credited with a distance of nearly 2.4 BLY. 

SHK 122 is less than a degree away and also exhibits a curvaceous form, although in this case more like a half-peanut. None of the members of SHK 122 are catalogued in LEDA as far as I can see, although there is a possible non-member (mag 18.3) close by at a distance of 758 MLY. What makes this cluster interesting are the two interlopers, one stellar, and one quasi-stellar, the latter at mag 19.4 with a redshift-implied distance of over 8 billion LYs. I can find no distance estimates for the galaxies themselves although the vertical line of galaxies to the left are at just under 2 BLYs. So in this one tiny 3'x2' region of the sky we have the coincidence of a foreground star from our own galaxy, a cluster of galaxies at some intermediate distance, and a very distant quasar.  

You can find them at these coordinates:

SHK 122: 11h 43' 18.0" +57 17' 20.8"

SHK 123: 11h 44' 41.4" +57 30' 20.5"

Capture credits: SX Lodestar X2 mono, Quattro 8", AZEQ6, laptop running LodestarLive v0.12 and USB-cable ;-)

Thanks for looking

Martin

[xtreemchaos]

great images and imfo, thats really getting out there. thanks for sharing. charl.

[nightvision]

Great stuff!  Going deep is just so mind bending.  

Where are you getting the ID charts?

[laudropb]

Very nice report. Thanks for this informative post.

[Martin Meredith]

Thanks everyone.

Great stuff!  Going deep is just so mind bending.  

Where are you getting the ID charts?

These are some charts I've constructed for this style of observing. See this thread.

Martin

[Ain Soph Aur]

Hi Martin. Very nice to see how you are pushing the limits here with a 8" f/4!. I am having so much fun with the Lodestars and LL that seriously thinking about moving to a C11 OTA, likely the largest SCT my CGEM DX will handle. I do have an Orion 10" f/4.7 OTA but have never tried mounting it on the DX, but since I am very interested in EAA PN's I think a C11 at native f/l and 6.6/3.3 reducers will offer more options.

[Ruud]

Thank you, Martin. I had never seen a Shakhbazian before.

[Martin Meredith]

Thanks Ruud. Although faint, I'm somehow drawn to the Shakhbazian groups as they tend to contain more galaxies in a smaller space than most of the Hickson groups, for instance. Also, they're typically not plotted and most have no listed magnitudes so it is always interesting to see just how they reveal themselves, usually bit by bit as the live stacking proceeds. What's more, they're for all the world like asterisms of faint stars or sparse faint clusters, so to imagine them as actually being very distant galaxies is all very exciting -- to me at least! Here's another group (SHK 129 in UMi, 8 components, the 8th at 12 o'clock being the faintest by far) that I captured last night:

Ain Soph Sur, I'm very happy with this particular scope as an all-rounder, particularly for really deep sky work. Combined with the Lodestar it gives 2.11"/pixel which is quite well matched to seeing much of the time. Actually, the above shot was at f/8 since I was using a Barlow.

It is amazing what such a modest scope can do with a sensitive camera *and* live stacking with LodestarLive -- critical to the success of the enterprise for those of us using alt-az mounts and impatient for near-live views! Here's the DSS image (from the Aladin app) for comparison. 

Your 10" f/4.7 sounds like a great scope for EAA. I have an old 10" f/6.3 primary quietly awaiting developments...

Martin