H-NGC6905 — Blue Flash
Planetary Nebula in Delphinus
About
The Blue Flash Nebula, a planetary nebula in Delphinus about 1.2′ across. Distance estimates range from roughly 5,500 to 8,500 light-years. Its central star is an oxygen-rich Wolf-Rayet-like star with a surface temperature near 150,000 K.
Imaging tips
- Too small to frame at ordinary focal lengths: it needs a long focal length and a fine pixel scale.
- One imager with twin 152 mm refractors at 0.533″ per pixel recorded it about 83 pixels wide, roughly 5% of the frame width.
- The same imager spent 32.3 hours in total, including 141 × 300 s of 3 nm OIII and 58 × 900 s of 5 nm Hα, plus colour and luminance.
- Best in July and August; it peaks near 60° from 50°N. Surface brightness is 20.5 mag/arcsec².
Facts
- Size
- 1′
- Magnitude
- 11.9
- Coordinates
- RA 20h 22.4m, Dec +20° 6′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Jul, Aug
- Peak altitude
- 60° from 50°N, 75° from 35°N