NGC 7635, also known as the Bubble Nebula, Sharpless 162, or Caldwell 11, is an H II region emission nebula in the constellation Cassiopeia. It lies close to the direction of the open cluster Messier 52.
The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow. It was discovered in 1787 by William Herschel.
Imaging telescopes or lenses: GSO RC 8" Carbon Tube Imaging cameras: ZWO ASI1600MM Pro Mounts: iOptron CEM70 Guiding cameras: ZWO ASI174MM mini Focal reducers: Astro Physics CCDT67 CCDT67 Software: PHD2 PHD 2 · N.I.N.A. Nighttime Imaging 'N' Astronomy · PixInsight Filters: Chroma Blue · Astrodon SII 3nm · Astrodon OIII 3nm · Astrodon Ha 3nm · Chroma Green · Chroma Red Astrodon Ha 3nm - 80x900s (20 hours) Astrodon Oiii 3nm - 60x900s (15 hours) Astrodon Sii 3nm - 60x900s (15 hours) Chroma Red - 60x60s Chroma Green - 60x60s Chroma Blue - 60x60s