I recently posted an image of NGC 4236, which also contained the smaller NGC 4250. When I took a closer look at that galaxy I could discern a faint but clear outer ring. There seems to be very few images of this galaxy and I have not found any image showing this outer ring or pointing it out. I have here made a crop and a careful reprocessing to make sure that the ring was not an artifact of, for example, Gradient Exterminator or Hi Pass filtering, but it was clear that the ring was there also after only stretching the image.
According to this interesting article ringed galaxies are very rare, only one in 10 000 is of this category:
https://bigthink.com/starts-with-a-bang/ring-galaxies/Since the original aim of this image was to look for a possible new PN, I was using a dual-band Ha+Oiii filter, which is not ideal for imaging galaxies as it blocks most of the visual light spectrum, but apparently the RASA 8 is enough of a light bucket to overcome this. Also, the galaxy is a bit on the small side for being imaged at a focal length of 400 mm, and this image is a drastic crop of the original.
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