Hemisphere:  Northern  ·  Constellation: Cepheus (Cep)  ·  Contains:  Iris Nebula  ·  NGC 7023
Getting plate-solving status, please wait...
Iris Nebula (NGC 7223, Caldwell 4), 



Iris Nebula (NGC 7223, Caldwell 4)

Getting plate-solving status, please wait...
Iris Nebula (NGC 7223, Caldwell 4), 



Iris Nebula (NGC 7223, Caldwell 4)


Imaging Telescopes Or Lenses
William Optics FLT 132
Imaging Cameras
iOptron CEM 70
Astrodon 36mm Filter Set (3nm Sii/Oiii, 5nm Ha)
William Optics Reducer Flattener 68III
PixInsight · NINA
Guiding Telescopes Or Lenses
Celestron OAG
Guiding Cameras
ZWO ASI174mm Mini

Acquisition details

Sept. 22, 2021
1300x60" (21h 40')
21h 40'
Avg. Moon age:
16.21 days
Avg. Moon phase:

Basic astrometry details

Astrometry.net job: 5025795

RA center: 21h01m39s.8

DEC center: +68°0852

Pixel scale: 0.524 arcsec/pixel

Orientation: 64.609 degrees

Field radius: 0.656 degrees

Resolution: 7495x5015

Data source: Backyard


This is the Iris Nebula, aka NGC 7023 shot from my backyard in Pasadena, CA. It is about 1300 light years from earth and is located near the constellation Cepheus towards the north.  This target is circumpolar which means that it never sets below the horizon. 

NGC 7023  is what is known as a reflection nebula which means that the dust cloud itself is not emitting light, rather it is reflecting (or absorbing) light from the stars within.  The dust particles are extremely fine and are smaller than dust particles on Earth. This is an extremely challenging target to get to look good because much of it is completely dark, so getting enough signal to noise in the dust to show gradients is extremely hard. 

This target is especially challenging shooting from my Bortle 8/9 backyard.  The best images I have seen of this are done from dark sites with observatory class telescopes with extremely long integration times (like 70h).  I have about 20 hours of data and even though I don’t have equal time on each filter, I decided to give it up because I thought I would have diminishing returns. It really is a beautiful target so maybe one day I’ll revisit it and perhaps try with a wider field and a darker site.

As mentioned before, I did not have even number of subs for each filter, partly because there was some clouds but I also just did not pay much attention night by night.

Subframe count (all 60s at -10C, 1x1 binned at 121 gain)
- 430G, 169B, 96R, 663L


Sky plot

Sky plot


Iris Nebula (NGC 7223, Caldwell 4),