Sharpless 135 is an emission nebula in Cepheus. Like most emission nebulae, it is dominated by hydrogen. There were moderate amounts of S II emission but not much O III emission.

This is in what I’m calling the HOOSY palette for lack of a better name. I saw this palette first presented by Adam Block and really like it. It has a natural-ish feeling to it though the S II emission is really a deeper shade of red than the hydrogen alpha emission. But, making the S II look yellow helps it stand out. The oxygen would be blue if there were enough of it to see but it’s so faint that it doesn’t really show – there’s a hint in the center.

This is 49h 5m of tricolor narrowband data with RGB stars. For the technical processing details, see astrobin.