HICKSON COMPACT GALAXY GROUPS

[AKB]

Lovely sights!

Distances, though, should surely be mega- rather than giga- …?!

[Mike JW]

Thanks Tony - distances duly adjusted.

 

[Bill S]

Not very original...

Last night was quite a good one so one of the objects I looked at was Hickson 68 - like Mike JW inspired by PatG's post. Definitely worth a look.

 

[PatG]

Great captures Mike and Bill,  

I will be having another look at these at the next opportunity, likely to try with the 200mm SCT next time. I think these objects will benefit from a bit more aperture.

Truly fascinating subject matter, when you start to scratch the surface - simply mind boggling - plenty of background reading to do around these compact groups I think. 

Pat

 

[Mike JW]

Hi Pat,

If you look at the start of this thread (as with all the threads that we have set up) you will find some useful resources.

Yep, go for the 200mm SCT, use an f6.3 reducer.......

Have fun,

Mike

[roelb]

HCG 68

Evo 8 @ f/5

ASI533MC-Pro

10 x 30 s

[Mike JW]

Thanks Roel - shot adds the wider fov and the PGC.

Mike

[Mike JW]

In complete contrast to Hickson 68, here is Hickson 50. This tiny group is also in the SHK catalogue - SHK 5. It it not far from the Owl Nebula.

So why is this group so tiny?  Distance is the key factor for this group.  Galaxies - e, b,,a and c are between 1.677 and 1.7 billion lyrs away. Galaxy d is further out at 1.721 billion lyrs.. C is the brightest at mag 18 and E is mag 20 ( not sure I believe that).

It would be interesting for you folk with 8" set ups to see what you can pick up and Tony for the wide fov to show just how small this group is - good luck.

Mike

[Martin Meredith]

Yes, a wonderful pairing (spot the Hickson)

[Mike JW]

Martin - excellent to have the view of both. Shows the value of the 8" set up.

Mike

[Mike JW]

Hickson 56 (Arp 322 and VV150)

b,c,d an e are between 361 and 369 million lyrs away. a is further out at 375 million lyrs.

The PGC galaxy is way out there at 2.655 billion lyrs - it must be big and bright to have so easily picked it up.

On the second shot I have labelled up some of the galaxy fuzz spots. The two with no magnitude - no idea if they are galaxies.

Mike

[roelb]

HCG 50 which I imaged March 25 in Bortle 7

6 SE @ f/5

13 x 10 s

 

[PatG]

A few Hickson's from last night. Conditions somewhat tricky with a lot of dew / condensation to start with followed by frost. couldn't feel my fingers by the time I packed up.

Hickson 68. I was keen to try this again, having been enthused / motivated by others vastly superior captures on this thread.

Definitely some improvement in detail from my previous observation, helped by larger scope.

An object was moving across the FOV during time I was observing this cluster and not sure what it could be- I'm somewhat perplexed as it doesn't look like a satellite. I think it looks quite at home in this field of view!

 

 

 

Next is Hickson 61 Sometimes referred to as 'the Box'. A tight / compact cluster of 4no galaxies., Reading up on this - 3 members of this group including NGC 4169 bottom left are at a distance of circa 170 mly whilst the elongated galaxy upper LHS (NGC 4173) is much closer at circa 43 mly so is not a physical member of this group.

 

Lastly Hickson 57. A lovely grouping and a real pleasure to observe. Copeland's Septet +1. Circa 400mly.

  

 

 

[Mike JW]

Quite clearly aperture makes a difference in detail observed, as seen in your shots. A lovely set of targets to enjoy. I tend to stack 20 to 30 subs to reduce the noise to a minimum.

As to the mystery object - slow moving satellite?

A great challenge is to visit all the Hicksons in a year - gets you around the sky and out at some very silly hours.

Mike

[roelb]

Starting February I was also imaging about 30 Hickson objects.

As a comparison here are mine with a ASI290MM at BIN 2 under Bortle 7 with a 6 SE @ F/5

HCG 68   27 x 10 s

HCG 61   21 x 10 s

HCG 57   25 x 10 s

[Mike JW]

Hickson 100 lies on the Pegasus/Pisces border.  The brightest galaxy is NGC 7803 - a lenticular with a mag of around 13.1.  It lies just 4 million lyrs away from Hickson b  - a bit like us and M31. The pair are around the 243-247 million lyrs away.  Galaxies c and d (mag15/16) are about 10 million lyrs further out and are about 6 million lyrs apart. The group of four galaxies that make up Hickson 100 are presumably gravitationally linked.

 

Mike

[Mike JW]

Last night I completed my tour of Pegasus Hickson Groups.

Hickson 99 (also known as VV 854) is a collection of 5 galaxies. Galaxy 'a' appears to have a double core - actually a line of sight star. Hickson 'c' looks suspiciously like a ring galaxy and in proper images it clearly has an outer ring and probably a bar. 'a', 'b' and 'c' are around the mag 14/15 but 'd' and 'e' are mag 17. They all have a similar redshift.

 

Hickson 96 (Arp 182, VV343). The lovely spiral 'a' is NGC 7674 and has a ring. It is given the designation as being peculiar - not obvious why until you view high resolution images - two lovely extending star trails from the northern side, like the antennae from an insect. The other bright galaxy is 'b', is NGC 7675 and is 4 million lyrs nearer - a true galaxy pair interacting gravitationally but the tails of 7674 could be caused by the interaction with the small galaxy 'c' just to the north and is about 5 million lyrs away.

 

 

Hickson 94 (Arp 170, VV 181) appeals to me because of the mess of 'a', 'b' an 'd' as well as the faint PGC galaxies in the fov.

Hickson 93 (Arp 99) is made up of 5 galaxies. 'a' (NGC 7550) and 'b' (NGC 7549) are Arp 99. NGC 7750 is being seriously disrupted due to its interaction with 7549 and also nearby 'c' (NGC 7547) - stars are being pulled out/flung out all over the place - not the place for a quiet weekend!!

Finally we come to Hickson 92 (Arp 319, VV 288) -Stephan's Quintet. What a fantastic image by the JWST a few weeks back.

Mike

 

 

[Martin Meredith]

Lovely collection of Pegasus Hicksons (always a harbinger of autumn). Stephan's is a particular favourite of mine (see avatar 🙂). You've managed to capture the long wisp that runs from top-right to lower-left of the group. As you say, great shot from the James Webb recently.I checked it out to see if the wisp ran on much more than in this image, but no, its more or less as you caught it and all the more remarkable for just over 3 minutes exposure. I also read that the lower left galaxy (I think its that one, from memory) is now definitely a foreground coincidence, as was long suspected. So really one has to imagine the group sans that one -- still rather spectacular.