Hemisphere:  Southern  ·  Constellation: Cetus (Cet)  ·  Contains:  NGC 7828  ·  NGC 7829  ·  NGC7828  ·  NGC7829  ·  PGC475  ·  PGC483  ·  PGC938317
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Arp 51 (with Arp 144), 



    
        

            Gary Imm
Arp 51 (with Arp 144), 



    
        

            Gary Imm

Arp 51 (with Arp 144)

Getting plate-solving status, please wait...
Arp 51 (with Arp 144), 



    
        

            Gary Imm
Arp 51 (with Arp 144), 



    
        

            Gary Imm

Arp 51 (with Arp 144)

Imaging telescopes or lenses: Celestron EdgeHD 11

Imaging cameras: ZWO ASI 1600MM Cooled 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:July 15, 2020July 16, 2020

Frames:
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: 24.87 days

Avg. Moon phase: 22.74%


Astrometry.net job: 4233832

RA center: 0h 6' 16"

DEC center: -13° 26' 52"

Pixel scale: 0.276 arcsec/pixel

Orientation: -2.020 degrees

Field radius: 0.131 degrees


Resolution: 2627x2190

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

Data source: Backyard

Description

This image captures a pair of Arp objects in the constellation of Cetus at a declination of -13 degrees. This is one of the closest pairings of Arp objects in the entire Arp catalog of 338 objects. Both of these objects are Astrobin Debut Objects. Each object contains two galaxies.

Arp 51 is the face-on spiral galaxy at image center, with a very faint companion on the arm just above and left of the core. The main galaxy is about 30 arc-seconds wide. There is no distance information available on either the main galaxy or the companion. My guess, based on the detail in the spiral structure, is that it is about twice as far away as Arp 141, which would put this galaxy at about 100,000 light years in diameter. Dr. Arp categorized this in his category of Spiral Galaxies – Small, High Surface Brightness Companions on Arms. The main galaxy is MCG-2-1-24, and the faint companion slightly above and left is ChaBG 69. Both are magnitude 15.

Arp 51 may be my least favorite Arp object. The companion is barely visible. There is no distance information available for these pair, so it is not clear to me that it is actually a nearby companion. The main galaxy does not look very disturbed to me. This object seems a stretch for Dr. Arp's famous collection. There are plenty of more interesting peculiar galaxies which did not even make the cut.

Arp 141 is the interesting pair of magnitude 14.5 galaxies to the upper left. The elliptical galaxy (lower left of pair) is NGC 7829, while the spiral galaxy is NGC 7828. These galaxies are located about 260 million light years away. Like the galaxy of Arp 51 each galaxy of this object is about 30 arc-seconds wide in our apparent view, which corresponds to a diameter for each of about 50,000 light years. Dr. Arp categorized this in his category of Elliptical Galaxies – Material Emanating from Elliptical Galaxies. For more of a description of this object as well as a comparison mouseover, please go here: Arp 141 .

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