H-NGC1931
Emission Nebula in Auriga
About
The Fly Nebula lies in Auriga, roughly 7,500 light-years away. Gas and dust there glow both by emission and by reflecting starlight, around a cluster only 2 million years old. Its small Trapezium of hot stars recalls Orion. William Herschel found it in 1793. It is in the Herschel 400 list.
Imaging tips
- Only 3–4′ across, so it is too small to frame: use a long focal length and a fine pixel scale.
- As an emission nebula it suits narrowband. One imager recorded only Hα and OIII, 51 × 10 minutes each over four nights, after noting that the glow is concentrated in a few narrow lines.
- Nearby sits IC 417 (the Spider), so wide frames pair the two. One imager used a 386 mm lens and 5.25 hours of Hα, OIII and SII in 300-second subs.
- Best in November and December, passing near 74° altitude from 50°N.
Facts
- Size
- 3′
- Magnitude
- 10.1
- Coordinates
- RA 5h 31.4m, Dec +34° 14′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Nov, Dec
- Peak altitude
- 74° from 50°N, 89° from 35°N