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Arp 228, 


            Gary Imm

Arp 228

Getting plate-solving status, please wait...
Arp 228, 


            Gary Imm

Arp 228

Imaging telescopes or lenses: Celestron EdgeHD 11

Imaging cameras: ZWO ASI 294 MM Pro

Mounts: Astro-Physics Mach1GTO

Guiding cameras: ZWO ASI 174 MM Mini

Software: Main Sequence Software Sequence Generator Pro  ·  Pixinsight  ·  Stark Labs PHD2 2.6.3

Filters: Astrodon Green 31mm Gen2 I-Series  ·  Astrodon Blue 31mm Gen2 I-Series  ·  Astrodon Lum 31mm Gen2 I-Series  ·  Astrodon Red 31mm Gen2 I-Series

Accessory: Celestron OAG  ·  ZWO EFW 2″X7  ·  MoonLite Focuser for EdgeHD 11

Dates:Jan. 17, 2021Jan. 18, 2021

Astrodon Blue 31mm Gen2 I-Series: 30x120" (1h) (gain: 120.00) -20C bin 2x2
Astrodon Green 31mm Gen2 I-Series: 30x120" (1h) (gain: 120.00) -20C bin 2x2
Astrodon Lum 31mm Gen2 I-Series: 60x120" (2h) (gain: 120.00) -20C bin 2x2
Astrodon Red 31mm Gen2 I-Series: 30x120" (1h) (gain: 120.00) -20C bin 2x2

Integration: 5h

Avg. Moon age: 4.78 days

Avg. Moon phase: 23.79%

Basic astrometry details job: 4243442

Resolution: 2884x2146

Locations: Backyard (Mag 20.8 - Bortle 4.5), Onalaska, Texas, United States

Data source: Backyard


This Astrobin Debut Object is an anchor galaxy of a galaxy cluster located 225 million light years away in the constellation of Pisces at a declination of +11 degrees. The 13.7 magnitude shell elliptical galaxy is IC 162. The shell elliptical galaxy spans 1.3 arc-minutes in our apparent view, which corresponds to a diameter of 90,000 light years.

This galaxy was classified by Dr. Arp into the category of Galaxies – Concentric Rings. The rings are the most interesting aspect of this object. When I started imaging, I thought that elliptical galaxy rings were simply an artifact introduced by over processing low-gradient elliptical galaxies. I now know that these rings are real shells and not artifacts, present in about 10% of elliptical galaxies (typically large one). The first shell was discovered in 1980.

Scientists believe that these shells are formed by galaxy collisions between a large elliptical and a smaller galaxy. The gravitational interaction causes waves of interstellar material to compress and spread out, producing the shells. I have a hard time understanding why galaxy collisions result in such excellent symmetry of each shell around the core.

Three shell surfaces, from inner region to outer in declining brightness, are visible to me in this image, although I do see hints of a few more. My collection of Shell Galaxies is here.

IC 162 looks like it has a 15 magnitude spiral companion (MCG+2-5-39) located slightly below and left, but this galaxy is 25 million light years further away at 250 million light years and therefore is not interacting with it.

Several other galaxies are also seen in the image and are a similar distance away from us. My favorite is UGC 1263 to the upper right, which looks like a grand spiral surrounded by a ring.

Finally, I like the bright orange double star just right and above image center (PGC 1380995). Except that when I check numerous sources for the star data, they tell me that this is galaxy LEDA 1380995. I think that must be an error.