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Cosmic Challenge: Abell Galaxy Cluster 426


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Phil Harrington's Cosmic Challenge

Abell Galaxy Cluster 426

December 2017

Phil Harrington

This month's suggested aperture range

Large scopes

10- to 14-inch (25cm to 36cm)

Target

Type

RA

DEC

Constellation

Magnitude

Size

AGC 426

Galaxy cluster

03 18.6

+41 30.0

Perseus

--

190'

 

Not long after I got my first "good" telescope, my 8-inch Criterion RV-8 Dynascope Newtonian reflector, as my Christmas gift in 1971, I became fascinated with the Perseus Galaxy Cluster.

One reason I am so fond of this collection of more than 500 galaxies is that the cluster grows as the telescope's aperture increases.  Small backyard scopes will show the two big kids on the block, NGC 1272 and NGC 1275, but even the largest amateur instruments fail to show all of the "little guys."

Above: Autumn star map from Star Watch by Phil Harrington.

 

Above: Finder chart for this month's Cosmic Challenge.

Chart adapted from Cosmic Challenge by Phil Harrington.
Click on the chart to open a printable PDF version in a new window.

Also known as Abell Galaxy Cluster 426, the Perseus Galaxy Cluster lies close enough to the plane of the Milky Way that the surrounding field is strewn with nearby stardust, which creates a very pretty overall effect.  There are plenty of hidden treasures scattered throughout cluster's full 190' expanse.  How many can you pick out in your telescope?

At about 230 million light years away, the Perseus galaxy metropolis is easy to find just 2° east-northeast of the Demon Star, Algol [Beta (β) Persei].  The brightest of the bunch, NGC 1275, shines at about 12th magnitude and lies just 2' east of an 11th-magnitude field star at the heart of the cluster.  Through your telescope, as through my 10-inch, NGC 1275 will look like a small, slightly elliptical glow that is punctuated by a bright stellar core.

When we gaze upon that small blemish, we are seeing a seething system in uproar, a galaxy that is emitting tremendous amounts of X radiation.  The full story behind NGC 1275 was first unveiled in 1943, when Carl Seyfert included it in his list of galaxies with active nuclei.  NGC 1275 is also included as 3C 87 in the Third Cambridge Catalog of quasars and radio sources, published in 1959 (revised in 1976).  And not just any radio source, mind you, but the second strongest in the entire sky -- only Centaurus A (NGC 5128) is stronger.

Studies now reveal that filamentary jets of material are erupting from the core of NGC 1275 and discharging into space at greater than 5.3 million miles per hour (2,400 kilometers per second).  Hubble images reveal what the fuss is all about.  We are not looking at one galaxy when we view NGC 1275; rather, we are looking at two separate galaxies that are intimately embraced by gravity.  Photographs clearly show the disrupted disk of a dust-laden spiral galaxy cutting through a large elliptical galaxy at speeds approaching 7 million miles per hour (3,000 kilometers per second).  In the process, gravitational tidal forces distort each galaxy, compressing huge clouds of interstellar matter and triggering new star formation.

After NGC 1275, the next brightest member of the Perseus clan is NGC 1272.  You will find it just 5' to the west.  Although NGC 1272 is listed at visual magnitude 11.7, you may feel, as I do, that its surface brightness is at least a full magnitude lower.  My most pleasing view of NGC 1272 through my 10-inch is at 106x.

Above: Sketch of the central portion of AGC 426 through the author's 18-inch (46cm) refractor.  Compare this view to the chart above, noting the flipped orientation.  NGC 1275 is the largest galaxy, seen right of center, while NGC 1272, at number 2, is left of center.

While its magnitude is only 13.2, NGC 1273 is actually easier to see than NGC 1272.  The difference is in the apparent size.  NGC 1273 is only half the diameter of its larger, but dimmer neighbor.  The resulting higher surface brightness (magnitude 12.5 versus 13.5) helps to make this little spiral an easier catch than the larger elliptical.  All three galaxies form a triangle at the center of the cluster.

A fourth very faint, distended patch of light actually turns that triangle into a parallelogram.  This dimmest member of the four is actually two galaxies, NGCs 1277 and 1278, separated by less than 50".  By increasing magnification to around 175x and waiting for steady seeing, both should be distinguishable as individual objects, with larger and brighter NGC 1278 lying southeast of NGC 1277.

In between NGC 1278 and NGC 1273, just 2.7' northwest of NGC 1275, is NGC 1274, a tough test indeed.  Notes made through my 13.1-inch (33.2cm) at 125x recall simply a very faint, very small blur.

NGC 1270 lies further southwest of NGC 1272.  That same night through my 13.1-inch, I recorded it as a "dim, poorly concentrated glow."  To its west are NGC 1267 and NGC 1268, a pair of even fainter challenges.

See that 10th-magnitude star 7' north of NGC 1275?  Look just 1' to its east for dim NGC 1281.  Can you spot it?  Seeing its tiny disk, which measures just 0.9'x0.4' across and shines at magnitude 13.3, is tough enough, but the scattered light from that star can really get in the way.  If you have an eyepiece with an occulting bar, you might give it a try here.

Once you conquer the galaxies described above, branch out on your own to find even more.  The table below lists all of the galaxies in AGC 426 that are brighter than magnitude 14.5, which is a reasonable cut-off point for 10- to 14-inch telescopes, while the chart plots the cluster's population center.

Object

RA

Dec

Magnitude

Size

UGC 2598

03 14.1

+41 17.5

14.4p  

1.5'x0.5'

IC 301

03 14.8

+42 13.4

14.2p

1.2'x 1.2'

UGC 2608

03 15.0

+42 02.2

13.7p

0.9'x 0.7'

UGC 2614

03 15.3

+42 41.8

14.3p

1.6'x 0.7'

NGC 1250

03 15.4

+41 21.3

12.8v  

2.2'x 0.8'

UGC 2617

03 16.0

+40 53.2

13.8p

2.5'x0.8'

UGC 2618

03 16.0

+42 04.5

14.5p

1.2'x 0.4'

IC 309

03 16.1

+40 48.3

14.5p

0.9'x 0.9'

IC 310

03 16.7

+41 19.5

12.7v

1.4'x 1.4'

NGC 1260

03 17.5

+41 24.3

14.3b

1.1'x 0.6'

PGC 12254

03 17.9

+41 27.1

13.9v

0.7'x 0.5'

IC 312

03 18.1

+41 45.3

14.4p  

1.4'x 0.7'

NGC 1265

03 18.3

+41 51.5

12.1v  

1.7'x 1.4'

NGC 1267

03 18.7

+41 28.1

14.1   

0.8'x 0.8'

NGC 1268

03 18.7

+41 29.3

14.2p  

1.0'x 0.7'

UGC 2654

03 18.7

+42 18.0

14.2p

1.4'x 0.5'

NGC 1270

03 19.0

+41 28.2

13.1v  

1.0'x 0.8'

NGC 1271

03 19.2

+41 21.2

13.9v  

0.7'x 0.3'

NGC 1272

03 19.4

+41 29.5

11.7v  

1.8'x 1.8'

NGC 1273

03 19.4

+41 32.4

13.2v  

1.0'x 0.8'

IC 1907

03 19.6

+41 34.8

14.2v  

0.9'x 0.8'

NGC 1274

03 19.7

+41 32.9

14.0v  

0.8'x 0.4'

NGC 1275

03 19.8

+41 30.7

11.9v  

2.2'x 1.8'

NGC 1278

03 19.9

+41 33.8

12.4v  

1.4'x 1.0'

NGC 1277

03 19.9

+41 34.4

13.4v  

0.8'x 0.4'

NGC 1281

03 20.1

+41 37.8

13.3v  

0.9'x 0.4'

NGC 1282

03 20.2

+41 22.0

13.9b  

1.2'x 0.9'

NGC 1283

03 20.3

+41 23.9

13.5v  

0.9'x 0.6'

UGC 2686

03 21.0

+40 47.9

14.4

0.9'x 0.4'

UGC 2689

03 21.5

+40 48.1

14.1

1.4'x 0.5'

NGC 1293

03 21.6

+41 23.6

14.5b  

0.8'x 0.8'

NGC 1294

03 21.7

+41 21.6

14.3b  

1.0'x 1.0'

UGC 2698

03 22.0

+40 51.8

13.9p

1.0'x 0.6'

UGC 2717

03 24.6

+40 41.5

14.3p

1.0'x 0.8'

IC 320

03 26.0

+40 47.4

14.6p  

1.2'x 1.0'

UGC 2733

03 26.1

+41 15.2

14.5p

1.0'x 0.6'

 

As you can see, there are plenty of other, mostly smaller and fainter systems, waiting for you.

Have a favorite challenge object of your own?  I'd love to hear about it, as well as how you did with this month's test.  Contact me through my web site or post to this e-column's discussion forum.

Until next month, remember that half of the fun is the thrill of the chase.  Game on!

 



About the Author:

Phil Harrington writes the monthly Binocular Universe column in Astronomy magazine and is the author of 9 books on astronomy.  Visit his web site at www.philharrington.net to learn more.

Phil Harrington's Cosmic Challenge is copyright 2017 by Philip S. Harrington.  All rights reserved.  No reproduction, in whole or in part, beyond single copies for use by an individual, is permitted without written permission of the copyright holder.

 


  • okiestarman56 and nicknacknock like this


6 Comments

Photo
nicknacknock
Dec 07 2017 06:34 AM

Nice one Phil!

 

On the bucket list - yes, I have a Sky Safari list appropriately labelled "Bucket List"!

    • PhilH likes this

500 galaxies...what did I do to you, Phil?  Are you trying to kill me via sleep deprivation?  

 

Oh well, I guess there are worse ways to go than seeing how deep one can peer into an Abell Galaxy Cluster.

 

Thanks for the article, I suppose I need to start marking up that A4 Uranometria chart so that I am ready to go really deep.   

 

Kudos for listing v, b, and p where known.  V is often 0.5 to 1.0 mag brighter than b or p so this can have substantial impact on visibility for those with smaller scopes and/or in poorer skies.

    • PhilH likes this

And now this, just when I thought knocking off 60 of M31's globular clusters in one night with the 17.5" was a nice accomplishment. Turns out that was just a drop in the bucket (list).

Thank you, Phil. Abell Clusters are my favorite objects! Ah, yes! I looked at A426 this past Oct18/19, with the JMI RB-16 binos. Here's from my journal: "1281, etc. Perseus Cluster, loaded with galaxies! Individual galaxies tough among stars at 102x. So, yes, I do see it pretty well, but recall the 29, under great conditions was much easier. Night Vision definitely helps, shows myriad galaxies in field, ten, at least distinct ones vs like two with the Panos at 102x. But, the NV impression is WAY different [80x]. The galaxies (vs stars) have soft halos and all have star-like, softish cores (ie the NIR penetration). The NV is not aesthetic, but certainly distinguishes galaxies from stars. Good Night! ~fin~"  Then, just last night, Dec 10th, I reviewed all of my astrophoto negatives from 1984-1992. Quite a few Abells in there too!  Tom

Ummm... Phil, your annotation to the eyepiece sketch, "the author's 18-inch (46cm) refractor." REFRACTOR?! If so, WOW!  Tom

Photo
Dave Mitsky
Yesterday, 02:28 AM
The last time that I observed A426 was on the night of November 24th. I had a brief look at the center of the cluster through a 25" Obsession Dob belonging to a fellow CAS member. I would have tried to do a better count than I did but the position I was in on the ladder was a bit uncomfortable.

Dave Mitsky


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