See later version (2020) HERE
NGC 7635, also called the Bubble Nebula, Sharpless 162, or Caldwell 11, is a 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, the 15 ± 5 M☉ 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. The star SAO 20575 or BD+602522 is thought to have a mass of 10-40 Solar masses.
With an 8 or 10-inch (250 mm) telescope, the nebula is visible as an extremely faint and large shell around the star. The nearby 7th magnitude star on the west hinders observation, but one can view the nebula using averted vision. Using a 16 to 18-inch (460 mm) scope, one can see that the faint nebula is irregular, being elongated in the north south direction.
The full FoV image below shows (in the top right corner): NGC7538.....which is interesting.
NGC 7538, near the more famous Bubble Nebula, is located in the constellation Cepheus. It is located about 9,100 light-years from Earth. It is home to the biggest yet discovered protostar which is about 300 times the size of the Solar System. It is located in the Perseus Spiral Arm of the Milky Way and is probably part of the Cassiopeia OB2 complex
Imaging telescopes or lenses: Takahashi FSQ106ED
Imaging cameras: QSI 6120i
Mounts: Takahashi EM 400 Temma 2
Guiding telescopes or lenses: Takahashi FS 60 CB
Guiding cameras: QHY CCD QHY 5 II
Focal reducers: Takahashi QE 0.73x
Software: PHD 2, Pleiades Astrophoto PixInsight , Sequence Generator Pro SGP
Filters: Astrodon Ha 3nm, Astrodon OIII 3nm, Astrodon SII 3nm,
Accessories: Robofocus Focuser, ATIK EFW2
Original Resolution: 4170 x 2775
Dates: 29th Aug - 4th Sep '16
Frames:
Astrodon Ha 3nm: 27x1200" bin 1x1
Astrodon OIII 3nm: 27x1200" bin 1x1
Astrodon SII 3nm: 27x1200" bin 1x1
Integration: 27 Hours
Center (RA, Dec):(350.142, 61.216)
Center (RA, hms):23h 20m 34.189s
Center (Dec, dms):+61° 12' 58.808"
Size:1.94 x 1.3 deg
Radius:1.167 deg
Pixel scale:1.64 arcsec/pixel
Orientation:Up is 180 degrees E of N
With an 8 or 10-inch (250 mm) telescope, the nebula is visible as an extremely faint and large shell around the star. The nearby 7th magnitude star on the west hinders observation, but one can view the nebula using averted vision. Using a 16 to 18-inch (460 mm) scope, one can see that the faint nebula is irregular, being elongated in the north south direction.
The full FoV image below shows (in the top right corner): NGC7538.....which is interesting.
NGC 7538, near the more famous Bubble Nebula, is located in the constellation Cepheus. It is located about 9,100 light-years from Earth. It is home to the biggest yet discovered protostar which is about 300 times the size of the Solar System. It is located in the Perseus Spiral Arm of the Milky Way and is probably part of the Cassiopeia OB2 complex
Imaging telescopes or lenses: Takahashi FSQ106ED
Imaging cameras: QSI 6120i
Mounts: Takahashi EM 400 Temma 2
Guiding telescopes or lenses: Takahashi FS 60 CB
Guiding cameras: QHY CCD QHY 5 II
Focal reducers: Takahashi QE 0.73x
Software: PHD 2, Pleiades Astrophoto PixInsight , Sequence Generator Pro SGP
Filters: Astrodon Ha 3nm, Astrodon OIII 3nm, Astrodon SII 3nm,
Accessories: Robofocus Focuser, ATIK EFW2
Original Resolution: 4170 x 2775
Dates: 29th Aug - 4th Sep '16
Frames:
Astrodon Ha 3nm: 27x1200" bin 1x1
Astrodon OIII 3nm: 27x1200" bin 1x1
Astrodon SII 3nm: 27x1200" bin 1x1
Integration: 27 Hours
Center (RA, Dec):(350.142, 61.216)
Center (RA, hms):23h 20m 34.189s
Center (Dec, dms):+61° 12' 58.808"
Size:1.94 x 1.3 deg
Radius:1.167 deg
Pixel scale:1.64 arcsec/pixel
Orientation:Up is 180 degrees E of N
Sky Plot
Annotated Image
Full FoV - Original Image
A closer look at NGC 7538