I wanted to capture this object a long time ago, but actually decided to start after update from OSC to monochrome camera.
Image on Astrobin
Own remote observatory. AZ-EQ6 mount, ED80 (520mm at 1/6.5), Atik383L+. Guilde - OAG with QHY5 camera.
Baader L: 42 x 600s;
Baader R: 24 x 600s;
Baader G: 24 x 600s;
Baader B: 26 x 600s;
Baader Ha: 40 x 1800s;
Total exposure - 39 hr.
Captured in SGP, processed in FitStacker, Pixinsight.
SH2-173 is a HII region with a diameter of 77 light years, approximately 8800 light-years away from Earth. It is located in the constellation of Cassiopeia in the Perseus arm, on of the main arms of our Milky Way.
Due to its resemblance to the mask the nebula is often called the "Phantom of the Opera" nebula.
On the full size image there is a NGC103 open cluster and small nebula SH2-172 (in right-bottom corner).