HDW 2 (Hartl-Dengel-Weinberger 2), also known as Sharpless 2-200 and PNG 138.1+04.1, is a quite old planetary nebula (PN) in the constellation Cassiopeia at RA 3hr 11m 29s and DEC +62d 45m 5s. The bright part of the object has a diameter of about 6', north is at the top left.
According to W. A. Weidmann and R. Gamen, who have examined the central stars of different PNs, the central star of HDW 2 is a binary star.
The color of the object is a mixture of blue/green OIII and red/magenta Ha. The Planetary Nebula is almost spherical with pronounced stripes and a darker area to the south, surrounded by a thin fissure. What looks like an outer bright H-Alpha ring or halo is probably the edge of an extended spherical shell from the earlier explosive event. This halo reaches up to a small open cluster of stars, Trümpler 3.