Go / no go for deep skyGo / no go for deep sky imaging
Iris Nebula (NGC 7023)
reflection nebula in Cepheus
The Iris Nebula is a blue reflection nebula in Cepheus, lit by a bright young star. Beyond the blue petals lies a much larger field of faint dust clouds that appear only in a long exposure from a dark sky.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- NGC 7023
- Type
- reflection nebula
- Constellation
- Cepheus
- Size
- 18′ across
- Brightness
- Magnitude 7.1
- Distance
- about 1,300 light-years
- Peak month (any location)
- Aug
- Typical prime months
- May to Oct
- Difficulty
- Intermediate
- Filter
- No filter (broadband); a UV/IR-cut or L filter is enough
Pick a saved location or share your device location. Your coordinates are used only to calculate tonight and are not stored. To save locations, use the planner.
How to image Iris Nebula
- No narrowband filter: it is a broadband target.
- Very long total exposure brings out the surrounding dusty clouds, which is where the pictures become special.
- Cepheus is high in the sky for northern observers through the autumn.
Framing: what focal length?
NGC 7023 is small, so a "60% of the frame" focal length would be impractical. Here is how much of an APS-C frame it covers at common long focal lengths; expect to crop.
| Focal length | Share of the frame width |
|---|---|
| 1,000 mm | about 22% |
| 2,000 mm | about 45% |
| 3,000 mm | about 67% |
How high does it climb from your latitude?
The highest point NGC 7023 reaches in the sky. Above about 60° is excellent, 30° to 60° is workable, and under 30° you are looking through a lot of air.
| Latitude | Highest point | Rating |
|---|---|---|
| 55°N (Scotland, Alaska) | 77° | High in the sky |
| 45°N (Minneapolis, Milan) | 67° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 57° | Workable |
| 25°N (Miami, Cairo) | 47° | Workable |
| 35°S (Sydney, Santiago) | below horizon | Never rises |
Also worth imaging
Want a GO / NO-GO verdict for tonight, with clouds, moon, seeing and a full dark-window timeline?
Open the planner