NGC 1961

About image
NGC 1961 is a galaxy in Camelopardalis constellation.
Its distance is 180 million light years and its apparent size is 4'x3'; it is the largest member of a small group of ten galaxies.
Due to its perturbed form on the southern spiral arm, it was also classified like Arp 184.
However there is no trace of an interaction with a companion.
Radio observation suggests that NGC 1961 is indeed an "intruder" inside the small galaxy group: by entering the group, this galaxy piles up the gas in the group medium, compressing it on its southern side, leading to the perturbation on the spiral arm that we see in the image.
(source: The Cambridge Photographic Atlas of Galaxies)

Technical data
Optics         Celestron C9.25 Edge HD f/10
Mount        10Micron GM1000 HPS
Camera         Atik 4000 with Starlight Xpress filter wheel 5 positions
Filters       Baader 50.8 unmounted
Guiding system     OAG LB Astro Proxima with Lodestar
Exposure details   L 18x600" bin1 -20C
Total integration   3h
Acquisition      Maxim, PHD2
Processing      Pixinsight 1.8, Photoshop CS5
SQM-L        21.00    
Location        Pian dell'Armà (Italy)
Date            20 September 2015

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