Hemisphere:  Southern  ·  Constellation: Fornax (For)  ·  Contains:  NGC 922  ·  PGC3080368  ·  PGC785512  ·  PGC9172
Getting plate-solving status, please wait...
NGC 922, 


            Gary Imm
NGC 922, 


            Gary Imm

NGC 922

Getting plate-solving status, please wait...
NGC 922, 


            Gary Imm
NGC 922, 


            Gary Imm

NGC 922

Imaging telescopes or lenses: Celestron EdgeHD 11

Imaging cameras: ZWO ASI 1600MM Cooled Pro

Mounts: Astro-Physics Mach1GTO

Guiding cameras: ZWO ASI174MM

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: ZWO M68 OAG  ·  ZWO EFW 2″X7  ·  MoonLite Focuser for EdgeHD 11

Dates:Nov. 6, 2020Nov. 7, 2020

Astrodon Blue 31mm Gen2 I-Series: 30x120" (1h) (gain: 139.00) -20C bin 1x1
Astrodon Green 31mm Gen2 I-Series: 30x120" (1h) (gain: 139.00) -20C bin 1x1
Astrodon Lum 31mm Gen2 I-Series: 60x120" (2h) (gain: 139.00) -20C bin 1x1
Astrodon Red 31mm Gen2 I-Series: 30x120" (1h) (gain: 139.00) -20C bin 1x1

Integration: 5h

Avg. Moon age: 20.61 days

Avg. Moon phase: 65.98%

Astrometry.net job: 4081249

RA center: 2h 25' 3"

DEC center: -24° 47' 31"

Pixel scale: 0.282 arcsec/pixel

Orientation: -3.921 degrees

Field radius: 0.160 degrees

Resolution: 3525x2086

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

Data source: Backyard


This object is a rarely imaged peculiar galaxy located 140 million light years away in the constellation of Fornax at a declination of -25 degrees. The galaxy spans 1.5 arc-minutes in our apparent view, which corresponds to an actual diameter of about 70,000 light years. It is about 30 degrees from face-on to us.

This object is a collisional ring galaxy, one of my favorite types. It may be the nearest such object to us. The galaxy has distinctive features of a off-center impact from a smaller galaxy – the outer ring structure created by propagating density waves, spoke-like arm fragments, an off-center star-forming bar, and a distinctive tidal plume pointing up and to the right. This plume has a faint "umbrella" shape, like that of the Umbrella Galaxy (Arp 189).

In many cases, the other colliding galaxy has been absorbed or is otherwise not visible. But in this case, the likely hit-and-run offender is seen at the upper right corner of the image. This galaxy (2MASXI J0224301-244443) is the same distance away as NGC 922. This small object is 15,000 light years in diameter.

Perhaps I just have an overactive imagination, but if I look closely at the tidal plume, I can envision where the small galaxy burst through the disk of NGC 922. The plume appears to split, with a void at about the 2 o'clock position. The void width is the same width as the diameter of the small galaxy. It is interesting that Dr. Arp did not include this amazing object in his Peculiar Galaxy collection.

For those who may be interested in seeing more obscure objects, my entire collection of 170 Astrobin debut objects is here.