Sh2-115
HII Region in Cygnus
About
An emission nebula in Cygnus, about 2–2.5° from Deneb in the northwest direction. Its glowing gas is mainly lit by the young cluster Berkeley 90 on the eastern side. Sources put it between about 7,500 and 9,800 light-years away.
Imaging tips
- About 25′ across: at 970–1620 mm on APS-C (1490–2480 mm full frame) it fills a third to half of the frame.
- An emission nebula, so narrowband suits it. In one 4-hour SHO image (300 s subs) the Hα was strong while OIII and SII were very faint and noise was a concern.
- One imager shooting a 132 mm f/7 refractor (about 924 mm) also caught Abell 71 in the frame; it was once listed as a planetary nebula and is now thought to be an HII cloud linked to Sh2-115.
- Best in July and August; it passes almost overhead, about 87° altitude from 50°N.
Facts
- Size
- 25′
- Magnitude
- —
- Coordinates
- RA 20h 35.0m, Dec +47° 2′
- Framing, APS-C
- 970–1620 mm
- Framing, full frame
- 1490–2480 mm
- Best months
- Jul, Aug
- Peak altitude
- 87° from 50°N, 78° from 35°N