Sh2-308 — Dolphin Head Nebula
HII Region in Canis Major
About
A bubble in Canis Major about 5,000 light-years away, nicknamed the Dolphin Head, carved by the fast winds of EZ CMa, a Wolf-Rayet star at its centre. NASA gives its age as about 70,000 years and its width as roughly 60 light-years; the star is nearing a supernova.
Imaging tips
- Sources give the size as about 35′ × 35′, slightly larger than the full Moon.
- NASA's narrowband image shows the faint glow dominated by ionised oxygen, so include OIII; one imager used 3 nm Hα and OIII filters and mapped them to a HOO palette.
- The star at the centre of the bubble varies between magnitude 6.71 and 6.95, so expect a bright point in the middle of the frame.
- Best from December to April; it stays low, peaking near 16° from 50°N.
Facts
- Size
- 35′
- Magnitude
- —
- Coordinates
- RA 6h 53.0m, Dec −23° 56′
- Framing, APS-C
- 690–1150 mm
- Framing, full frame
- 1060–1770 mm
- Best months
- Jan, Dec
- Peak altitude
- 16° from 50°N, 31° from 35°N