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Hemisphere:  Northern  ·  Contains:  NGC 4712, NGC 4725
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NGC 4725, The One-Armed Galaxy, 


            Steven Bellavia
NGC 4725, The One-Armed Galaxy
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NGC 4725, The One-Armed Galaxy

Technical card

Imaging telescopes or lenses: Celestron C6 SCT

Imaging cameras: ZWO ASI533MC Pro

Mounts: Sky-Watcher EQ-6R Pro SynScan

Guiding cameras: ASI224MC

Focal reducers: Celestron f/6.3 Focal Reducer

Software: Pleiades Astrophoto PixInsight  ·  Stark Labs Nebulosity 4.2  ·  Annie's Astro Actions V7  ·  Noel Carboni's Astro Tools for PhotoShop Noel Carboni Actions  ·  IDEIKI AstroPhotography Tool (APT)  ·  PHD2 Guiding

Filters: Astronomik L2 UV/IR Cut

Accessory: Celestron OAG #93648

Dates:April 20, 2020

Frames:Astronomik L2 UV/IR Cut: 58x180" (gain: 100.00) -5C bin 1x1

Integration: 2.9 hours

Darks: ~30

Flats: ~30

Flat darks: ~30

Avg. Moon age: 27.19 days

Avg. Moon phase: 6.07%

Bortle Dark-Sky Scale: 4.00

Mean SQM: 20.80

Mean FWHM: 3.20

Temperature: 5.00

Basic astrometry details job: 3497165

RA center: 12h 50' 27"

DEC center: +25° 29' 38"

Pixel scale: 0.750 arcsec/pixel

Orientation: 1.092 degrees

Field radius: 0.315 degrees

Resolution: 2244x2021

Data source: Backyard


NGC 4725, the "one-armed galaxy", is an intermediate barred spiral galaxy with a prominent ring structure  41 million light-years away in the constellation Coma Berenices.  While most spiral galaxies, including our own Milky Way, have two or more spiral arms, NGC 4725 has only one. NGC 4725 is a Seyfert Galaxy, suggesting an active galactic nucleus containing a supermassive black hole.
It is magnitude 10.1 and fairly large at 10'7" x 7'6", a little larger than the Black-eye galaxy, M64,  though about 1.5 magnitudes dimmer.



Steven Bellavia
License: None (All rights reserved)

Sky plot

Sky plot


NGC 4725, The One-Armed Galaxy, 


            Steven Bellavia