B33 — Horsehead Nebula
Dark Nebula in Orion
About
The Horsehead Nebula, a dense dust cloud in Orion about 1,375 light-years away, seen as a dark silhouette against the glowing hydrogen of IC 434. Williamina Fleming spotted it on a photographic plate in 1888; Barnard catalogued it later as B33.
Imaging tips
- Too small to frame: it spans only a few arcminutes, so use a long focal length. In a wider view it sits beside Alnitak and the Flame Nebula.
- The dark shape only shows against the red glow behind it, so Hα is the usual choice. One 11-hour image used Hα with short RGB frames.
- Alnitak is the brightest star in a wide frame of this area, with the Flame Nebula just below it.
- Hα frames can be taken under moonlight; save colour frames for moonless nights. Best in December.
Facts
- Size
- 6′ × 4′
- Magnitude
- —
- Coordinates
- RA 5h 40.9m, Dec −2° 27′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Dec
- Peak altitude
- 38° from 50°N, 53° from 35°N