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Contains:  NGC 7023
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NGC 7023 - Iris Nebula, 


            Gary Imm
NGC 7023 - Iris Nebula

NGC 7023 - Iris Nebula

Technical card

Resolution: 4274x3222

Dates:Nov. 4, 2018

Astrodon Blue 31mm Gen2 I-Series: 60x10" (gain: 139.00) -20C bin 1x1
Astrodon Blue 31mm Gen2 I-Series: 120x30" (gain: 139.00) -20C bin 1x1
Astrodon Green 31mm Gen2 I-Series: 60x10" (gain: 139.00) -20C bin 1x1
Astrodon Green 31mm Gen2 I-Series: 120x30" (gain: 139.00) -20C bin 1x1
Astrodon Red 31mm Gen2 I-Series: 60x10" (gain: 139.00) -20C bin 1x1
Astrodon Red 31mm Gen2 I-Series: 120x30" (gain: 139.00) -20C bin 1x1

Integration: 3.5 hours

Avg. Moon age: 26.23 days

Avg. Moon phase: 11.84% job: 2356284

RA center: 315.439 degrees

DEC center: 68.052 degrees

Pixel scale: 0.782 arcsec/pixel

Orientation: 269.210 degrees

Field radius: 0.581 degrees

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

Data source: Backyard


This object is a beautiful blue reflection nebula located 1400 light years away in the constellation of Cepheus. A bright 7th magnitude star (HD 200775) illuminates the core of the nebula. This true color image shows that the dominant color of the brighter reflection nebula is blue, as is true for most reflection nebulae, characteristic of dust grains reflecting starlight. The darkest areas in this image are places where dust blocks the light from the stars behind it. The pretty blue petals of the Iris Nebula span about six light-years.

I like the nature of the "windows" that seem to be carved through different parts of the cloud, especially towards the bottom where the background sky can be fully seen. I don't understand why there are such distinct boundaries - I do not see such behavior in earthly clouds. The L-shaped window at the bottom is similar to the T-shaped window of the Keyhole Nebula, which itself is not a dark cloud but is empty space as this nebula is. In that case, stellar jets are believed to be responsible for clearing the "window", so perhaps that is the case for this nebula as well.

The toughest part about obtaining this image is getting enough exposure time for the nebula without overexposing it due to the intensity of the bright central star. For this image, I took two sets of exposures and combined them to reduce the overexposure of the central star, but in the end I don't think this approach made much difference.



Gary Imm
License: None (All rights reserved)

Sky plot

Sky plot


NGC 7023 - Iris Nebula, 


            Gary Imm