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, 2020 , May 24, 2020 , May 25, 2020 , May 26, 2020 , May 27, 2020 , May 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.
Description: Darkened background (hate those uncalibrated LCD screens!), sharpened galaxy a bit. Hope it's not too cartoonish.
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