C4 — Iris Nebula
Reflection Nebula in Cepheus
About
A reflection nebula in Cepheus, about 1,300 light-years away, spanning roughly 6 light-years. It is lit by the young binary star HD 200775, and Spitzer found fullerenes (C60) in it, a first for interstellar space.
Imaging tips
- About 18′ across: 1,350–2,240 mm on APS-C frames the nebula, and a wide field also shows the faint dust around it.
- Narrowband is not an option for this faint region; use a one-shot-colour camera or LRGB broadband.
- Faint dust is the challenge: the Galactic Hunter write-up suggests several nights under Bortle 4 skies or darker; its two projects ran 4.5 hours of 5-minute subs and 15 hours of 10-minute subs.
- With a one-shot-colour camera, the bright star beside the nebula can leave a diffraction artefact; one imager removed it in PixInsight.
- Best around July and August; it peaks near 72° from 50°N.
Facts
- Size
- 18′
- Magnitude
- 7.0
- Coordinates
- RA 21h 1.6m, Dec +68° 10′
- Framing, APS-C
- 1350–2240 mm
- Framing, full frame
- 2060–3440 mm
- Best months
- Jul, Aug
- Peak altitude
- 72° from 50°N, 57° from 35°N