Sh2-140
HII Region in Cepheus
About
A small emission nebula in Cepheus, about 2,500 to 3,000 light-years away, beside the dark nebula LDN 1204, at that cloud's southwest side. Its crescent look is attributed to that dark cloud lying in front and blocking some of the red glow behind.
Imaging tips
- Only about 10′ across, so it needs 2420–4040 mm on APS-C or 3710–6190 mm on full frame to fill a third to half of the frame.
- One imager shot 8 frames of 10 minutes through a light-pollution suppression filter, about 80 minutes in all, with a one-shot colour camera.
- Another imager took 12 h 23 m in SHO plus RGB stars and noted that the fainter outer regions would need considerably more integration.
- Another image used 6 × 20 min of Ha added to about 3 hours of RGB, from a 12.5-inch scope.
- Best around August and September, peaking near 77° altitude from 50°N.
Facts
- Size
- 10′
- Magnitude
- —
- Coordinates
- RA 22h 19.1m, Dec +63° 17′
- Framing, APS-C
- 2420–4040 mm
- Framing, full frame
- 3710–6190 mm
- Best months
- Aug, Sep
- Peak altitude
- 77° from 50°N, 62° from 35°N