Cohen 129 or RNO 129 or GN 21.00.4 belongs to the small group of yellowish/orange nebulae. The unusual coloration is caused by the nearby star whose light intensively illuminates the dense dust of the much larger dark nebula complex LBN 552 in a small area. The dark nebula LBN 552 itself is part of an extensive dust area which is also referred to as “the fighting dragons”.
The distinctive and unusual color of Cohen 129 was my main motivation to target this area near the North Celestial Pole. The brightest parts of Cohen 129 could already easily be seen “live” while viewing the 12-second subs during acquisition. This reflection nebula is therefore almost certainly one of the brightest representatives of its kind, at least in the northern half of the sky.
In particular, a very small, elliptical part of the nebula, which sits directly at the star, separated from the fan-shaped main part, is so tiny and bright that it could easily be mistaken for a star and therefore overlooked in my final image. This is why here comes a less stretched close-up:
In contrast to Cohen 129, the dust formation of LBN 552 and its even fainter surroundings proved to be an extremely difficult target under my backyard conditions. Since so far I had been able to image other dark nebulae with less difficulties, while processing I was surprised at how difficult this one was to work out in a somewhat attractive way. Thanks to the necessary heavy stretching, I reached the limits of my OSC-camera; the background was initially covered with several red/blue blotches, which took some time to at least push them mostly below visibility - mono cameras with color filters have a clear advantage at those dim targets for sure.
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