Pickering’s Triangle in Cygnus
Pickering’s Triangle is the middle part of the Cygnus Loop, a supernova remnant with an age of about 15’000 years. It is much fainter than NGC 6992 (Eastern Part) and NGC 6960 (Western Part) and has no NGC number assigned. It was discoverd by Williamina Fleming but credited to Edward Pickering, the director of her observatory.
The image is a combination of narrowband data (Ha and OIII) and color data. North is up in this image.
[description from wikipedia]