Hemisphere:  Northern  ·  Contains:  Bubble Nebula  ·  NGC 7635
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            Gary Imm


            Gary Imm


Imaging telescopes or lenses: Takahashi TOA-130NFB

Imaging cameras: ZWO ASI6200MM Pro

Mounts: Astro-Physics Mach1GTO

Guiding cameras: ZWO ASI174MM

Software: Pixinsight  ·  Main Sequence Software Sequence Generator Pro  ·  Stark Labs PHD2 2.6.3

Filters: Chroma Red 2" unmounted  ·  Chroma SII 3nm  ·  Chroma OIII 3nm  ·  Chroma Ha 3nm  ·  Chroma Blue 2" unmounted  ·  Chroma Green 2" unmounted

Accessory: ZWO M68 OAG  ·  ZWO EFW 2″X7  ·  Takahashi Flattener TOA-67  ·  Feathertouch Focuser Boss II Electronic Focusing Control

Dates:Sept. 10, 2020Sept. 11, 2020Sept. 12, 2020Sept. 13, 2020

Chroma Blue 2" unmounted: 30x120" (gain: 0.00) -5C bin 1x1
Chroma Green 2" unmounted: 30x120" (gain: 0.00) -5C bin 1x1
Chroma Ha 3nm: 24x300" (gain: 100.00) -5C bin 1x1
Chroma OIII 3nm: 24x300" (gain: 100.00) -5C bin 1x1
Chroma Red 2" unmounted: 30x120" (gain: 0.00) -5C bin 1x1
Chroma SII 3nm: 24x300" (gain: 100.00) -5C bin 1x1

Integration: 9.0 hours

Avg. Moon age: 23.70 days

Avg. Moon phase: 34.25%

Astrometry.net job: 3931554

RA center: 23h 16' 38"

DEC center: +60° 24' 36"

Pixel scale: 0.774 arcsec/pixel

Orientation: 271.858 degrees

Field radius: 1.217 degrees

Resolution: 9432x6280

Locations: Backyard (Mag 20.8 - New Moon), Onalaska, Texas, United States

Data source: Backyard


This narrowband image captures a series of deep sky objects in the constellation of Cassiopeia at a declination of +60 degrees.

The largest object in this image is Sh2-157. This bright emission nebula is located 8000 light-years away and is over 200 light-years across. This nebula has been described as a ring nebula surrounding the Wolf-Rayet star WR 157. WR 157 is a member of the Markarian 50 star cluster. Although I can see the emission fronts expanding from the WR 157 source star, the surrounding structures are very complex and it seems a bit simplistic to me to just describe this fascinating object as a ring nebula.

The most striking object in this image is NGC 7635, the Bubble Nebula, which is located about 7,000 light years away. Although it looks small in the image, the bubble diameter is about 7 light years across. A closeup image of the Bubble is shown here. This object is caused by a stellar wind emitted from the source star (another Wolf-Rayet star). These WR stars expel a significant amount of mass, resulting in the expanding gas bubble which is contained by the molecular cloud which surrounds it.

Several additional deep sky objects, including a star cluster (NGC 7510), a planetary nebula (PLN 110-0.1), a reflection nebula (GN 25.13.3) and 2 emission nebulae (Sh2-157A & Sh2-159) are identified on the annotated image.



Gary Imm
License: None (All rights reserved)


  • Sh2-157, 


            Gary Imm
  • Sh2-157, 


            Gary Imm


Description: Astrobin Mouseover

Sky plot

Sky plot




            Gary Imm