Sh2 173 is a faint emission nebula from the Sharpless catalogue. This image was taken on August 27, 2017 at my Creedmoor site. Sh2-173 is located in Cassiopeia, near open cluster NGC103. Open cluster Mayer 1 is a loose group of 20 or so stars scattered across the face of Sh2-173. It is often referred to as the Phantom of the Opera Nebula.