Cepheus and Cassiopeia

The Cepheus and Cassiopeia regions are one of the most confusing regions in hydrogen-alpha, and I've split them into one overview map and two detail areas. The region is confusing because there are so many visible nebulae here. Cepheus is not obscured by the Rift dust clouds, unlike Cygnus, Vulpecula and the Dark Zone. Moreover, there are two or possibly three very different complexes here that overlap in the image.

The Cepheus region is relatively nearby at less than 1000 parsecs. The Cassiopeia arc lies in the outer galaxy at about 2500 parsecs, and makes up the most visible part of what is often called the Perseus arm. Apparently visible behind the Cassiopeia arc is a third huge molecular cloud complex located about twice as far away at about 5200 parsecs (however see below for some questions about its existence). There are also many other nebula visible in the Cepheus images that are located far away in the outer galaxy, at distances that may be larger than 9000 parsecs.