Hemisphere:  Northern  ·  Contains:  NGC 5474  ·  NGC5474
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NGC 5474, 


            Cedric Raguenaud
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Imaging telescopes or lenses: Skywatcher 300/1500

Imaging cameras: QHYCCD 183C

Mounts: Skywatcher EQ8 pro

Guiding telescopes or lenses: TS-Optics OAG

Guiding cameras: ZWO ASI120MM

Focal reducers: Baader MPCC Mark III Coma Corrector

Software: Gimp 2.10  ·  PixInsight 1.8 Ripley

Dates:May 23, 2020May 24, 2020May 25, 2020May 26, 2020May 27, 2020May 28, 2020

Frames: 125x600" (gain: 16.00) bin 1x1

Integration: 20.8 hours

Avg. Moon age: 3.16 days

Avg. Moon phase: 13.38%

Bortle Dark-Sky Scale: 3.00

Mean SQM: 21.71

Astrometry.net job: 3598176

RA center: 14h 5' 2"

DEC center: +53° 39' 20"

Pixel scale: 0.584 arcsec/pixel

Orientation: 81.097 degrees

Field radius: 0.208 degrees

Resolution: 2048x1538

Locations: ORCA Observatory, Near Matha, Charente-Maritime, France

Data source: Own remote observatory

Remote source: Non-commercial independent facility


This is NGC 5474. It is a dwarf galaxy satellite of M101. It's about 15 hours of integration (it's faint I need a bit more).

It's fascinating in that it's one of the few galaxies that look lopsided. The reason has long been assumed that it was the gravitational pull of M101 nearby that created it.

However, a paper published in Astronomy & Astrophysics in February this year ("The strange case of the peculiar spiral galaxy NGC 5474, New pieces of a galactic puzzle" by M. Bellazzini et al.) casts doubts on that explanation. There are several reasons:
- the galaxy has arms (even a faint bar), where recent star formation has occured (they're blue). These arms are centered on the bulge of the galaxy, therefore it might not be lopsided.
- there is a half circle of older stars SW of the bulge (left of the bulge in the image). That half circle is off-centre. M101 could have a responsibility in this, but it doesn't really explain it well. Another possible explanation is that the dwarf galaxy interacted with another dwarf galaxy a few Gyrs ago (goven the positions and velocities of M101 and NGC 5474, their interaction would be a few 100Myrs ago, so too late).
- it could even be that that region IS another dwarf galaxy. The bulge itself could be another dwarf galaxy. Data is currently insufficient to know.



Cedric Raguenaud
License: Attribution-NonCommercial-ShareAlike Creative Commons


  • NGC 5474, 


            Cedric Raguenaud
  • Final
    NGC 5474, 


            Cedric Raguenaud


Description: Darkened background (hate those uncalibrated LCD screens!), sharpened galaxy a bit. Hope it's not too cartoonish.

Sky plot

Sky plot


NGC 5474, 


            Cedric Raguenaud