Object: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 "bubble" is created by the stellar wind from a massive hot, 8.7 magnitude young central star, SAO 20575 (BD+60°2522). 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. Distance from Earth is 7100-11000 light-years.

This image was a difficult one primarily because of the smoke from the west coast forest fires permeating the otherwise clear skies.

Taken: September 14,19 & 20, 2020

Telescope: Astro-Tech 14” RC with Starizona Apex-ED L 0.65x focal reducer

Mount: Paramount ME II unguided

Camera: ZWO ASI1600MM-Pro (cooled to -10C; Unity Gain) Bin 1×1.

Focuser: Moonlite Nitecrawler

Rotator: Moonlite Nitecrawler

Filters used: Chroma Ha-OIII-SII 3nm narrowband with a ZWO 2″ 7 position filter wheel

Exposures: 137×120 seconds Ha; 140×120 seconds OIII; 138×120 seconds SII for a total exposure time of 13.5 hours; calibrated with 38 dark frames, 40 flat frames and 40 flat-dark frames.

Seeing Conditions: 3/5 average. Bortle 5 region. Moon was 10.46% full. Impaired by smoke from west coast fires.

Image capture and telescope control: Sequence Generator Pro and TheSkyX Pro

Processed with PixInsight, Photoshop CC 2020

Astrobin