Iris Nebula
NGC 7023 / Caldwell 4
The Iris Nebula is a reflection nebula, which means it is made of dust and is illuminated by starlight (in the visible spectrum). In this case, by the bright star visible in the center. The nebula itself is very bright, just below the human eye’s perception threshold (which is about 10 photons hitting the same cell in a tenth of second). It is 6 light-years in diamater and is about 1,300 light-years away from Earth.
Technical details
| Details | |
|---|---|
| Telescope | Skywatcher Esprit 100ED (f/5.5) |
| Filter | Astrodon LRGB Gen2 E-Series |
| Coma corrector | - |
| Field flattener | Skywatcher Esprit (1x) |
| Camera | QHYCCD 268m, -15°C, Mode 1, Gain 0, Offset 30 |
| Resolution | 6132x4035 (cropped) |
| Light frames | L: 40/40 (100s), 1h6m |
| R: 6/7 (300s), 30m | |
| G: 4/7 (300s), 20m | |
| B: 6/9 (300s), 30m | |
| 2h26m total | |
| Flat frames | 16 each (3s, per channel brightness) |
| Darkflat frames | 32 |
| Dark frames | - |
| Bias frames | - |
| Location | Kalkalpen Nationalpark, Austria |
| Local time | 2023-08-11 21:40 - 00:04 (53 frames) |
| 2023-08-14 22:23 - 22:34 (3 frames) | |
| Field of View | 2°22' x 1°33' (rotation 109°) |
| Image Center | 21h01m46s +68°10'55 |