Object of the Week, January 22nd 2024 — The Box

[akarsh]

HCG 61 = The Box
Compact Group of Galaxies
RA: 12 12 26
Dec: +29 09 57

This compact group comprises of four galaxies, all with NGC designations:

NGC designation	Redshift (z)	Distance (Mly)	Size	Mag (V)
NGC 4169	0.0127	170	1.8' × 0.9'	12.34
NGC 4173	0.0037	33	5.0' × 0.7'	13.3
NGC 4174	0.0134	175	0.82' × 0.5'	13.6
NGC 4175	0.0131	182 (or 118?)	1.8' × 0.4'	13.4

In the above table, all data is from NED except for the magnitudes which are from SIMBAD. There is stark ambiguity between the redshift-based (182 Mly) and the redshift-independent (118 Mly) distance to NGC 4175. The 118 Mly distance is based on 3 references in NED, all three using the Tully-Fisher relation.

Of course, it is evident from the redshifts that NGC 4173 is a foreground galaxy, whereas the remaining three (likely) form a bonafide group with a distance of about 180 Mly.

There isn't much literature on the group as a whole, and I did not dig deep into the individual galaxies. One reference indicates that this is a relatively gas-rich group and notes the disturbed morphology of NGC 4175. That NGC 4175 has something interesting going on can be seen by looking at the POSSII Blue image:

HCG61.png
DSS2 Blue image of HCG 61. The cross hairs mark the knot in NGC 4175

I'm not sure what the knot marked in the above image is, but perhaps this is related to the disturbed morphology discussed in the reference. The legacy survey image seemingly doesn't give more insight into this knot:
HCG61Legacy.png
Legacy survey image of the group

This deep image from the Legacy survey however does show what look like tidal disturbances in NGC 4174 and NGC 4169, perhaps a result of their interaction.

Incidentally, SIMBAD lists a background (8.8 Gyr light travel) quasar of 20th mag shining through NGC 4173, named 2XMMi J121226.7+291117, perhaps a real challenge for Jimi Lowrey's 48".

This object was on my mind because of a recent observation made at a star party in south India, on the night of Jan 13 2024 using Jagan Gorti's 16" Hubble Optics telescope equipped with a Baader Hyperion zoom eyepiece. I logged "Spotted all 4 galaxies, a-c were continuous direct vision with a being brightest. d was hardest, continuous AV, elongated." The conditions were of subpar transparency and perhaps best described as Bortle 4. However, the beautiful arrangement of galaxies was well-appreciated by many of the visual observers gathered on the field.

But of course, this group is too amazing for me to have not observed it before. Surprisingly, I've only logged it twice in the past. On 29th March 2014, I observed the group from Bortle 2 skies in central Texas (near Pontotoc, TX) using my 18". I described it as "Easy, bright and nice!" while marking that NGC 4173's elongation was easily seen.

But the more interesting observation was a birthday treat on my 28th birthday! Through Jimi Lowrey's 48" telescope, I described the group as spectacular. My observation marks a "mild knot?" on NGC 4175 right where the knot lies, and notes a "sensation of a dark lane all through".

I am looking forward to seeing all the beautiful sketches you have of this group. Whereas most of you have seen it already, this group is perhaps worth re-visiting. If you haven't seen it yet, all the more reason to
GIVE IT A GO AND LET US KNOW

Clear Skies
Akarsh

[Raul Leon]

Hi,here's my observation from 4/28/2009: The Box aka HCG 61; (ngc 4169,4174,4173 and 4175) fairly bright, 4174 being the dimmest. I used a 10mm Radian at 198x with my 14.5 StarStructure f/4.3ngc 4169.jpg

[lamperti]

Have seen these with an 18 & a 20" reflector.
NGC 4169:"Brightest of three (NGC-4174 & 4175). Center is bright and solid. Harder to see full extension."
NGC 4174:"Fainter and oval in shape. Seen with NGC-4175 and 4169."
NGC 4175:"Seen with NGC-4174 & 4179. Dimmest of the three. Not quite round."
NGC 4173:"Transparency dropped but could still make it out, averted vision #3. Adjacent to a star to make it easier to find. PA ~ 160 [134]; " NGC-4173 is the largest of 3 galaxies; elongated, faded to edges."

[Clear Skies]

To my surprise, there's only one observation in my log for this beautiful group, that's not just a Hickson, but a Rose, a KTG, a Holmberg and a Vorontsov-Vel'yaminov group, too. It's also part of the galaxy cluster WBL 385 that includes a fifth galaxy: MCG+05-29-030, 11' to the west-southwest. Surprisingly, NGC4173 is listed a being part of that cluster, too, even though its redshift is quite a bit off. And if that's not enough, the group is also part of 17 member Lyon Galaxy Group 279, the "NGC4274 Group"; the namesake galaxy for that bunch is 1.7° to the east-northeast.

Truth be told, the historically first designation for this group really ought to be Rose 10; even Hickson pointed to it in his catalog notes. But it just happens that the Hickson list is much better known.

Hickson 61-1.jpg Hickson 61-2.jpg Hickson 61-3.jpg

Click here to download the guide.

My one observation was just before midnight on 27 April 2022 in the French Ardennes - 14" SCT @168x / 29':

All four galaxies are visible, a nice view.
A - NGC4169 is a NNW-SSE elongated glow, quite suddenly brighter in a relatively small core that is elongated in the same direction with a bright nucleus that is clearly visible without AV.
B - NGC4173 is a faint but clearly NE-SW extremely elongated streak, with AV brightest in the NW part.
C - NGC4175 is in line with B - NGC4173, a NW-SE elongated glow, with AV more elongated and with AV a faint central bulge is discernible that is slightly elongated in the same direction (almost round). No nucleus visible.
D - NGC4174 is a NE-SW elongated glow, the smallest galaxy of the group, brighter than C - NGC4175 is but fainter than A - NGC4169 is, quite suddenly brighter in a core that is elongated in the same direction, without AV the bright nucleus is visible.

I rated it 8/10.

[Don Pensack]

I've seen this group many times in my 12.5". I don't really have anything in my notes that would add to the above.
I first saw it in 1994 with an 8".
Given the magnitudes and the transiting altitude in the US, it might be visible with 5-6".
Has anyone seen the group with less than 8"?

[Steve Gottlieb]

Like Don, I've observed the group many times (brightest Hickson?), so here's are a couple of observations of UGC 7190 = MCG +05-29-030, which is only 11' or so southwest of The Box. But, as opposed to NGC 4173, which lies in the foreground of the other 3 members, its recessional velocity is twice as large. Still, it's cataloged as a member of WBL 385, which includes the other 4 members of The Box

13.1" (4/10/86): at 166x; faint, small, slightly elongated. A faint star is 30" off the NW edge. Located 4' ESE of mag 9 SAO 82171 and 10' WSW of the NGC 4169 quartet.

24" (5/22/17: at 282x; fairly faint, slightly elongated N-S, modestly brighter core gradually increases to a faint stellar nucleus. A mag 14 star is at the northwest edge [27" from nucleus].

[Uwe Glahn]

Never looked at it with smaller than 12.5-inch but with this aperture all members were visible.

The 16-inch shows the quartet with all its beauty and all the different elongations.

sketch: 16", 515x, NELM 6m0+
HCG61.jpg
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The 27-inch shows "c" (4175) with a stellar peak at the NW tip, "b" (4173) is clearly S-twisted with a longish offset nucleus but without the dark lane.

[Hickson observing project to HCG 61]