RA 23 16 04.08
Dec +60 02 06.0
Sharpless 157 is only a small star hop away from the much better known objects M52 (an open cluster) or the Bubble Nebula, NGC 7635. Its Sharpless designation is for many observers synonym with dimness and being at the edge of visibility, if at all. Sharpless 157 is none of it. If you have an OIII filter. Sh 157 was my "first contact" with the Sharpless catalog. It got started by a pioneering image by Richard Crisp in 2004, which was at that time one of the first narrowband composites.
Sh-157 is excited by the Wolf-Rayet star WR 157, though it appears to be not a classical wind-blown WR bubble. With OIII filter, the main filament forms a large and visually obvious milky streak that is surrounded by other fainter filaments, which are fun to explore.
DSS Image of Sh-157
The brightest OIII part of the nebula is the extension that trails from the central part for about one degree towards north. In the low power eyepiece equipped with OIII filter, this long feature is immediately visible upon field sweeping (as it is very large) as a long milky bar that usually requires moving your telescope to scan its entire length. Distinct markers are the fan shaped open cluster Markarian 50 to the west and NGC 7538, a very bright and distinct small nebula about one degree north of it.
Just east of this main part is another, smaller nebulous patch (OIII). West of the main filament is another shorter and fainter filament (OIII). South of it are another two large, but diffuse areas (best with H-beta), with a small bright knot in between. This knot (sometimes referred to as Sh2-157a) shines in HII and is a distinct object without filter or with H beta filter.
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Good luck and Great viewing!"