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Contains:  NGC 4747, NGC 4725, NGC 4712
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Arp 159, 


            Gary Imm
Arp 159

Arp 159

Technical card

Resolution: 3717x3004

Dates:March 27, 2019March 28, 2019

Astrodon Blue 31mm Gen2 I-Series: 120x30" (gain: 139.00) -20C bin 1x1
Astrodon Green 31mm Gen2 I-Series: 120x30" (gain: 139.00) -20C bin 1x1
Astrodon Lum 31mm Gen2 I-Series: 240x30" (gain: 139.00) -20C bin 1x1
Astrodon Red 31mm Gen2 I-Series: 120x30" (gain: 139.00) -20C bin 1x1

Integration: 5.0 hours

Avg. Moon age: 21.97 days

Avg. Moon phase: 51.93% job: 2631574

RA center: 12h 50' 27"

DEC center: +25° 30' 3"

Pixel scale: 0.783 arcsec/pixel

Orientation: 262.762 degrees

Field radius: 0.519

Locations: Backyard (Mag 20.8 - New Moon), Onalaska, Texas, United States

Data source: Backyard


This image captures a wonderfully complicated trio of galaxies in the constellation of Coma Berenices. Although I will only focus on the largest three galaxies in the image, many other smaller galaxies are also visible. In fact, most of the small orangish "stars" through the image are actually galaxies.

The smallest apparent diameter galaxy of the trio is NGC 4712, at the bottom center of the image. It is the same actual size as the largest galaxy in the center, at 135,000 light years in diameter, but is five times further away at 200 million light years so it appears much smaller to us. Even at this distance, its core, spiral structure and star clusters are clearly seen.

The largest galaxy, at the center of the image, is NGC 4725. It has a beautifully intricate structure. It is a barred spiral galaxy located 40 million light years away. This galaxy, which is tilted towards us at about 45 degrees, has many interesting features:
- It has a active galactic nucleus, which means the luminosity of the core is much brighter than normal.
- The central bar is actually a warped, curving structure. Scientists have identified that it actually consists of two bars, of two different sizes, rotating independently from each other.
- Surrounding the core region is a bright blue ring of star clusters, which contrasts nicely with the yellowish core.
- This galaxy appears to have only one very long arm, making 2-1/2 revolutions around the core.
- The above unusual structures are believed to be the result of gravitational interactions with NGC 4747, at the top right corner of the image.

NGC 4747 is about the same distance away from us as NGC 4725. We view this as an edge-on spiral galaxy, showing us its thick, mottled dust lanes. Like the other galaxies, it appears to have a yellowish core and blue spiral arms. The most interesting feature of the image to me are the tidal streams which are emanating from the outer reaches of the galaxy. The longest loop is extending away from NGC 4725, which is typical of these interacting galaxies. These loops and the disturbed disk are the reasons for the "Arp 159" designation of this galaxy.



Gary Imm
License: None (All rights reserved)

Sky plot

Sky plot


Arp 159, 


            Gary Imm