Arp 81 / NGC 6621 and 6622

Designation(s)Arp 81, NGC 6621, NGC 6622
Object Type(s)Galaxy
Relevant Catalog(s)All (Chron), Arp, NGC
Arp CategorySpiral galaxies with large high surface brightness companions on arms
Obs. Lat/Long42° 17', 073° 57'
ConstellationDraco
Date and Time Observed2024-09-02 21:28:00
InstrumentEdgeHD 8" f10-2,032mm FL
CameraASI294MC-Pro
Image DetailsUp is 179.6 degrees E of N. Total integration time was 20m 30s. Exposures 30s@305g, UV/IR Cut Filter. Darks subtracted, no flats. Dithered and recentered in SharpCap. No guiding.
DescriptionCaptured on a dark night but where clouds closed in and forced me to shut down early. Seeing was poor, and stars exhibited distorted shapes. Nevertheless, you can see clearly the pair of interacting spiral galaxies with one (6621) exhibiting a long arm separated from the spiral and connecting to the smaller one (6622), especially in the inverted image. The two certainly appear to be in the process of merging, and I would love to see a simulation of the relative motion which created the long, wrap-around separation of the arm. The bright, elongated object to the right of the arm-tip I take to be a distorted field star not a galaxy. Arp's remarks are "Companion resembles M 51 companion", which suggests a singular, large companion and confirms my field-star interpretation.
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