Sh2-27
HII Region in Ophiuchus
About
A huge, faint cloud of glowing hydrogen around the star Zeta Ophiuchi, one of the closest emission nebulae at about 440 light-years. The star is a runaway that was probably flung out of a binary, and it drives a bow shock through the surrounding dust.
Imaging tips
- Very large: at 50–80 mm on APS-C (80–130 mm full frame) it fills a third to half of the frame. Wider lenses suit it too; one 50 mm wide-field image covers about 19° × 13°.
- Red hydrogen glow, so use a narrowband Hα filter. One 50 mm image combined 5 × 12 min of Hα with 22 × 5 min of RGB, 170 minutes in all.
- Large and faint, with Zeta Ophiuchi, a bright star, at its centre; expect the star to need careful handling in processing.
- M107 lies about 54′ away in the same field. Dark Lynds clouds (LDN 260, 255, 234, 204) run through the lower left of the nebula.
- Best in May and June; it stays below about 27° from 50°N, so it is a low target in the north.
Facts
- Size
- 480′
- Magnitude
- —
- Coordinates
- RA 16h 35.9m, Dec −12° 43′
- Framing, APS-C
- 50–80 mm
- Framing, full frame
- 80–130 mm
- Best months
- May, Jun
- Peak altitude
- 27° from 50°N, 42° from 35°N
Nearby
- M107 · 53.9′ away