Caldwell 4 — Reflection Nebula in Cepheus
NGC 7023
About Iris Nebula
Description
The Iris Nebula (NGC 7023) is a bright reflection nebula in Cepheus, about 1,300 light-years away. It is illuminated by the young B-type star HD 200775 at its center. The blue reflection nebula spans about 6 arcminutes and is surrounded by a large region of dusty nebulosity.
Observing Tips
Visible as a hazy glow around a bright star in a 4-inch telescope. Larger scopes (8-inch and up) begin to show the nebula's shape. No nebula filter is needed since it is a reflection nebula. Best observed in autumn evenings.
History
Discovered by William Herschel on October 18, 1794. The Iris Nebula has become one of the most popular astrophotography targets, revealing intricate dust structures and beautiful blue hues in long exposures.
Fun Facts
The Iris Nebula contains polycyclic aromatic hydrocarbons (PAHs) in the surrounding dust. Deep images show red fluorescent emission from these carbon-based molecules alongside the blue reflected starlight.
Observe
1Properties
Position & Identifiers
2How easy to spot?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Medium+ | Medium+ | Medium+ |
| 150 mm Newton 150mm Newt. | Medium+ | Medium+ | Medium+ |
| Celestron C8 (203 mm SCT) C8 203mm | Medium+ | Medium+ | Medium+ |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
3Visibility
Set a location in User Settings to see visibility data.
4
Filter Response Guide
5
Eyepiece View
Iris Nebula · 10.0′×8.0′ · N up, E left
Explore
6
Surface Brightness
Discover
7
Light Travel Time Machine
8
Relativistic Travel
Community Photos (1)
Credit: Andreigusan This is a featured picture on the Persian language Wikipedia (نگارههای برگزیده) and is considered one of the finest images. See its nomination here. If you think this.... License: CC BY-SA 4.0. (Wikimedia Commons)
Skybred Mar 2, 2026
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
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