Object of the Week – AGC 1060, The Hydra Cluster

[Paul Alsing]

Object of the Week – AGC 1060, The Hydra Cluster

R.A.: 10 36 43.1 Dec.: -27 31 36 (NGC 3311)
Size: 3.5 'x 2.9, Magnitude: 11.7

I started this OoTW intending to report on Hickson 48, in Hydra, but while looking around the neighborhood, I was reminded that there are bigger fish to fry here! AGC 1060 is a subset of the much larger Hydra-Centaurus supercluster, and the center of this cluster is littered with galaxies that are fairly bright and tightly packed! A really fun area of the sky to turn off the drive, loosen the clutches and just cruise around. Here is a screenshot from SkyTools…

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… where the smaller central circle is 0.5 degrees just for reference, and the larger offset circle is supposedly the boundary of AGC 1060 (labeled here as ACO 1060 by SkyTools). Other sources tell me that AGC 1060 is much larger than as shown here, and contains 157 bright galaxies. You can see Hickson 48 up there about 30 arcminutes to the NNE, with its bright elliptical anchor galaxy IC 2597, and that group is magnified in the box at the upper right of the screenshot. The 3 companions of IC 2597, which are also part of AGC 1060, are a challenge to see!

Here is another screenshot from Megastar, showing only the central part of the cluster with more labeled objects…

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The brightest galaxies are NGC 3311, mag 11.6, NGC 3309, mag 12.6, and NGC 3312, mag 12.7, but there are a lot of others there just waiting to be tracked down. I had a blast roaming around in this area, which extends beyond the edges of my illustrations. Here is a list of AGC 1060 galaxies, which I borrowed from a Phil Harrington article (https://www.cloudynights.com/articles/cat/column/phil-harrington-s/cosmic-challenge-abell-galaxy-cluster-agc-1060-r3289)…

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As always, give it a go and let us know.

[Uwe Glahn]

With -27° DEC the group is simply to low for nearly every European astronomer. So I picked out two gems of the group.

NGC 3314 is perhaps one of the most fascinating galaxy pair in the whole sky, two objects in line, divided by around factor two when it comes to the real distances. I hunted this pair several years and it needs one of the best skies in the world plus 28-inch aperture, to see both galaxies as two clear objects.

sketch: 28", 520x, NELM 7m5+, Seeing II-III (Gamsberg/Namibia) (http://www.deepsky-visuell.de/Zeichnungen/NGC3314.htm)
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For HCG 48 I had to go to La Palma at 29° N. With 20-inch, a nice galaxy chain group was visible.

sketch: 20", 250x, NELM 7m0+, Seeing V (Puntagorda/La Palma) (http://www.deepsky-visuell.de/Zeichnungen/HCG48.htm)
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[Paul Alsing]

Uwe wrote; "With -27° DEC the group is simply to low for nearly every European astronomer".

I observed this from our local Anza Borrego desert, in eastern San Diego County, where this cluster culminates at about 30° above the southern horizon. On a clear night, there are usually no issues.

I really like your drawings, Uve!

[akarsh]

A very good OOTW choice, Paul. Here are my notes, observing with my 18-inch near the California Bay Area, so at about 36° N latitude. This was from April 2023.

I picked up 10 galaxies. A motivation to look at this group was to study the overlap NGC 3314A (the overlapping members are designated in Wikipedia as NGC 3314a and NGC 3314b, not to be confused with the other designation system NGC 3314A = ESO 501-46 combined for both members of the overlap, and NGC 3314B = PGC 87327 used by Steinicke). I found out about this overlap from one of Larry Mitchell's excellent TSP lists. Unfortunately, I was not able to discern any signs of the overlap in NGC 3314A. It looked like a run-of-the-mill edge-on. For some reason, the NGC galaxy NGC 3307, 13.5 mag, posed a lot of difficulty to discern. I was surprised, but Mark Wagner who was observing with me was having similar results with other NGC galaxies in that range, indicating poor transparency. It still seemed much harder than an NGC should be. The Dreyer description is "eeF" and Steve's notes concur on its difficulty, but it is still quite amazing that John Herschel discovered it with only an 18.3". By contrast, PGC 31537's core seemed easier. The 10 galaxies picked up were NGC 3308, NGC 3309, NGC 3311, NGC 3307, IC 629, NGC 3314A, NGC 3314B, NGC 3316 (2 galaxies, one pretty much stellar), PGC 31537.

[akarsh]

BTW, Adventures in Deep Space has a page on the cluster with Steve Gottlieb's notes: https://adventuresindeepspace.com/agc1060.htm

Looks like Albert Highe didn't have this cluster on his website.

[kisspeter]

A really fascinating group of galaxies. Unfortunately we only took a brief look at it in 2016 with the 24" at Hakos, Namibia (1-2 hours 4wd drive away from Gamsberg). Memories are fading quickly if I don't draw an object. But one thing I clearly remember is NGC 3314A. We were struggling with it for a couple of minutes. I can totally confirm Uwe's observation. With 24" aperture and not absolutely perfect seeing I could see dark spots, maybe even lanes on the body of NGC 3314A but it was simply not clear. A little better seeing and/or a little bigger scope would have been needed to really see the details and to be able to draw them. The view was not very far from that of Uwe's drawing just a little messed up.