Object of the Week Mar 25, 2012 - Hickson 56 along with Arp 214

Hickson 56 and NGC 3718 (Arp 214)

Hickson 56 11 32 39 +52 56 23 (center) z=0.27 (all five components are about 372 mly distant)
Component A (MCG +9-19-113) 11 32 46.7 +52 56 27 Mag 16.2b Size 1.3x0.2’
Component B (UGC 6527) 11 32 40.3 +52 57 01 Mag 16.2b Size 0.7x0.3’
Component C (PGC 35618) 11 32 36.8 +52 56 52 Mag 15.8b Size 0.7x0.4’
Component D (PGC 35615) 11 32 34.3 +52 56 53 Mag 16.8 Size 0.4x0.3’
Component E (PGC 35609) 11 32 32.8 +52 56 22 Mag 16.4b Size 0.5x0.3’

NGC 3718 (Arp 214) 11 32 35.0 +53 04 05 Mag 10.7v Size 9.2x4.4’ z= 0.003312 (~42mly)

Dr. Paul Hickson published a paper, “Systematic Properties of Compact Groups of Galaxies” in the Astrophysical Journal in 1982. This paper contained a list of 100 isolated compact group of galaxies ranging from quartets to octets. He used three main criterion to select his 100 groups; (1) Population - At least 4 members and all are within 3 magnitudes of each other, (2) Isolation – not part or near any larger groups, such as Abell Galaxy Clusters, (3) Compactness – Basically, only those that fairly compact would meet this criteria, of 26 mag/arcsec. His paper can be found here http://tinyurl.com/87b3aob

So after some time, amateur observers with large telescopes, started to take this “list” as a challenge list.

Steve Gottlieb already mentioned the history of the Arp Peculiar Galaxies. Dr. Halton Arp categorized Arp 214 as “Irregularities, absorption and resolution”

I’ve observed this group several times over the years. It is interesting to think that the Hickson group lies almost 10 times further away than Arp 214.

My observations are as follows:

Hickson 56 (22” f/4 reflector at 881x under NELM 6.5 skies)
One galaxy is separated from the rest (four other galaxies). The string of four, three visible, galaxies is in a string of about 60” long. This Group lies only 10’ south of NGC 3718, a very bright peculiar galaxy.
Component A (MCG+9-19-113) shows as a faint spindle with an almost stellar nucleus. It is about 60” long and averted vision gives maybe about 5” longer spindle. PA = 0˚.
Component B (UGC 6527) shows a small, faint, round disk with a diameter of about 15”. This forms a very close double galaxy with PGC 35618. This pair lies 1.5’ WNW from MCG+9-19-113.
Component C (PGC 35618) lies less than 15” west of UGC 6527 and is a very faint round disk of about 10” in diameter.
Component D (PGC 35615) – Not seen, but I’m not sure.
Component E (PGC 35609) – At 880x, this nearly stellar galaxy is seen only 50% of the time. It is found sitting 40” WSW of PGC 35615.

Attachment 136
Labelled DSS image of Hickson 56

Attachment 137
Eyepiece rendition with my 22" at 881x and 5.6' field

Arp 214 (22" f/4.1 reflector @ 184, 255, 305 and 377x under NELM 6.5 skies)
This one is a weird one, but fun to look at. At first it looked like an elliptical with a dust lane screaming across the middle and cutting its compact nucleus in half. Studying this with higher powers showed very faint arms with the north one a little brighter, but shorter. The dust lane is at PA = 120º. The round part is 2.5’ across and the both arms extend as much as 1.5’ from the edge of the disk.

Attachment 134
Eyepiece rendition of Arp 214 at 255x field 18.8

Attachment 135
Sloan image of both Arp 214 and Hickson 56

So the next time you are under a clear dark sky remember Hickson 56 and Arp 214 and,
"GIVE IT A GO AND LET US KNOW"

GOOD LUCK AND GREAT VIEWING!

Nice object selection Alvin. I have three observations of this group and it is interesting to see the difference in the sky with the same scope so I'll list the best observation and summarize the lesser one as I had the B,C,D members as running together without resolved cores. Third observation was a quick 'saw it' as I was after Ngc 3718 in a borrowed view in a 33" dob. All below are with 18" f/3.7 dob at 338x but the GSSP one was with TakLE 5mm and local one for un-resolved cores on B,C,D was 21.35 at a dark site (this implies non-ideal night there) using Nagler 5mm skies were clearly different.

Adin GSSP 6-23-2009 NELM 6.9 SQM 21.65
A 2EL Perpendicular to B/C line Very difficult.
B One of three in a tight line and this one shows core ok.
C One of three in a tight line and this one shows core averted.
D Not a very confirm-able observation. High mag shows core infrequently.
E Tiny round. At W end of this group and about as difficult as A member

Then from 2-19-2009 at a dark site in 'Willow Springs' but not ideal night with SQM 21.35 which is 'poor' for that site.
A Away from Group to the E with NS EL
B,C,D For each I wrote: Appears as EW smear with B,C,D all together, non-resolved
E Difficult. > 30% time averted.

My observations with a 18" from 16 years back pretty much mimic yours Mark, with "D" noted as "glimpsed a couple of times at the west edge of HCG 56C although not seen with 100% certainty."

Last April viewing through Jimi's 48", things were considerably easier :D

A: Fairly faint, fairly large, very thin edge-on ~6:1 N-S, ~60"x10", very weak concentration but no core or zones, fades at tips.
B: Fairly bright, fairly small, elongated 5:2 SW-NE, ~30"x12", sharply concentrated with a very bright, small nucleus. HCG 56C lies 34" WSW and HCG 56C is 46" WSW. A faint hazy extension off the SW end stretches towards HCG 56C.
C: Moderately bright, small, round, 15" diameter, contains a very small bright nucleus. Sandwiched between HCG 56B and HCG 56D.
D: Fairly faint, small, slightly elongated, 12"x9". Located just 12" E of the center of HCG 56C, though easily resolved. This is probably the faintest member of the quintet.
E: Fairly faint, small, round, 12" diameter.

Thanks Marko and Steve - it appears that I have some difficulty seeing component D (or B as depicted in my sketch). Looks like I have to look at it again. It has been a while since I've observed this object.

I observed Hickson 56 and Arp 214 last April 22 under decent skies (SQM 21.20 and ok seeing) and made the attached sketch. Given the sky conditions it was more of a challenge to see the dark lane through NGC 3718 than it was to see all the members of Hickson 56 - I'd love to have a look at these fascinating objects under a truly dark sky! 3718 looked best at 243x and Hickson 56 was best at 408x. NGC 3729 on the right in the sketch looked about the same at both magnifications.
Attachment 138

Definitely a fun group. In my 30", components C & D appeared as a single galaxy at lower power, only resolving into two separate objects above 400x. It's also worth noting that components B-E comprise Arp 322, part of the galaxy chains section of the Arp catalog.

Hi Alvin,

this is also a favorite Hickson of mine. And it was also one of the first ones that I had observed it with both my 14" 10 years ago and more recently with my 22" several times.

With 14" I could see the chain and distinguish some knots in it, though there was no clear resolution. If I recall it correctly, I could not see A with 14".

With 22", the chain is mostly resolved, with c and d forming a single clump under less than optimal conditions, same as in your observation. Under good conditions, c and d appeared separated. Very unexpectedly, A is the most difficult member in this group, even with 22". It is faint with low surface brightness and no clear core. This is very untypical.

Alvin,

- with my 16" I could not separate c and d, a was hard to detect (sketch
- with 27" c and d could be separate easily with high power, a was a wonderful 4:1 edge on, the sketch is in work (observation from last new moon period)

Hello all;

This is a fun group and I will certainly add it to my observing list once the Moon is out of the sky.

I have a request. I know this means very little to many of you, but it does mean a lot to those of us who organize our notes by constellation. Can the original poster please add in that information as part of that post? I would appreciate and I believe others will as well.

Clear skies to us all;
Steve Coe

I viewed this group in late October, 1992 from central Minnesota with my f4.5 18" Dob. I recall the very cold morning, about 4 am with the temp in the mid teens, and frost most of the way down the inside of my closed dob tube. All 5 galaxies were seen, though "a" was difficult and took several minutes to see as a pinpoint, and "c" and "d" were merged almost together.

On the last night of the 2012 TSP we viewed this group with Jimi's 48" and they were all separated and direct vision, just like an image in a magazine. Direct vision and immediately visible. 3718 had great detail and the tail pointed back to Hickson 56.

Dave Tosteson

Observing guides for NGC3718 Attachment 206 and Hickson 56 .

Cheers,


Victor

A little bit late but a target from the march new moon period - HCG 56 with 27" and 419x

Attachment 209

Quote:

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Originally Posted by Dave Tosteson

I viewed this group in late October, 1992 from central Minnesota with my f4.5 18" Dob. I recall the very cold morning, about 4 am with the temp in the mid teens, and frost most of the way down the inside of my closed dob tube. All 5 galaxies were seen, though "a" was difficult and took several minutes to see as a pinpoint, and "c" and "d" were merged almost together.

On the last night of the 2012 TSP we viewed this group with Jimi's 48" and they were all separated and direct vision, just like an image in a magazine. Direct vision and immediately visible. 3718 had great detail and the tail pointed back to Hickson 56.

Dave Tosteson

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Hi all,
i also had the chance to observe Hickson 56 with Jimis 48" during last night of TSP 2012 (thanks Jimi - it was a great experience). HCG 56 was an easy target; with direct vision i could see all components separated - same as Dave descriped.
With my 15" Obsession i observed HCG 56 two times under very good sky conditions in the austrian alps (about 8000ft elevation) - the chain was visible indirect, but without separation of components B,C and D. Component A was a "50% object" with averted vision (quite hard to see).

Clear skies
Marc