NGC7635 also known as the Bubble Nebula (other designations: SH-162, Caldwell 11) is an emission nebula in the constellation Cassiopeia, it was discovered in 1787 by William Herschel.

The bubble is created by the stellar wind from a massive hot young central star, it lies at a distance of 11.000 light years and measures 12 light years across.

Besides this nebula, also several other objects are visible in the image.
Open star cluster Messier 52 can be seen left of center.
The small and bright emission nebula above and to the right of the Bubble Nebula is NGC7538. The small filaments of nebulousity at bottom right belong to the object Sharpless 2-157

Other versions

Previous/older images:

Oct 03, 2011 – ST8300M (80mm TMB-2h)

Oct 14, 2007 – Canon 350D (8″ f4 GSO 2h6m)

Image data

Object info
Name NGC7635 – The Bubble Nebula
Type Emission nebula
Constellation Cassiopeia
Right ascension 23h 20m 48s
Declination +61° 12′ 06″
Distance 11.000 ly
Other designations Sh2-162, Caldwell 11
Image info
Image date Sep. 09, 2012
Light frames 8x 5 min. RGB (each) unbinned, 20x 6 min. UHC-S unbinned (Luminance)
Total integration 4h
Dark frames 18x
Flat frames 15x p. filter unbinned, created with an A3 size Posterpoweruk flatfield panel
Bias frames 15x
Software used CCDOps, CCDSoft, Maxim DL, Photoshop CS4
Processing CCDOPS was used for focussing. Image Acquisition was done using CCDSoft.
All separate frames were calibrated, aligned and stacked in MaxIm DL5 Pro.
Photoshop CS4 was used for further processing – curves adjustment, levels adjustment, etc.
Noel Carboni’s toolset was used as well (Local Contrast Enhancement, Deep Space Noise Reduction)
(L)RGB combine was done in Photoshop.
Equipment info
Telescope TMB/LOMO 80/480
Corrector Televue 2″ RPF 2804 flattener (FL: 528mm f/6.6)
Mount Losmandy G-11 Gemini
Camera SBIG ST-8300M
Guide camera Atik 1HS Mono
Guide scope Vixen VMC110L
Autoguide software PHD Guiding
Filters Baader 2″ RGB + UHC-S + IDAS LPS-P2
Location Landgraaf, The Netherlands
Image comments

All RGB exposures were taken through IDAS LPS-2 filter which was in front of the filter wheel.
Need to optimize backfocus distance