About image
NGC 7635 ia a nebula in Cassiopeia constellation, also called "Bubble Nebula" because of its shape.
It is an HII region, at whose southern vertex there is an empty structure, caused by the pressure of the radiation of a central blue star, whose stellar wind reaches 2000 km / s; it is a blue giant, which is also responsible for the ionization of the nebula, which then emits its own light. Its distance from the Sun is estimated at 11,000 light years.

Technical data
Optic            Celestron C9.25 Edge HD f/10
Mount          Losmandy G11 with Ovision worm and FS2
Camera           Atik 4000 with Starlight Xpress filter wheel 5 positions
Filters        Baader Ha 7nm and OIII 8.5nm, 50.8 unmounted
Guiding system      OAG LB Astro Proxima and Lodestar
Exposure details    Ha 15x900" bin1 -20C
                                      OIII 13x900" bin1 -15C
Total integration    7h
Acquisition        Maxim, PHD2
Processing        Maxim, Photoshop CS5
SQM-L         18.5    
Location         Home terrace (Rescaldina, Italy)
Date            2 September 2013, 13 September 2014