Sh2-157 — Lobster Claw Nebula
HII Region in Cassiopeia
About
The Lobster Claw Nebula, an emission nebula in Cassiopeia near the Bubble Nebula, about 8,000 light-years away by one source. The small nebula Sharpless 157a, around the Wolf-Rayet star WR 157, sits near its lower pincer.
Imaging tips
- About 60′ across, so 400–670 mm on APS-C or 620–1030 mm on full frame frames it.
- The open cluster NGC 7510 is about 50′ away, so it sits nearby rather than comfortably in the same field; one 2-panel mosaic also took in M52 and the Bubble Nebula.
- An emission nebula, so narrowband suits it. One page describes it as especially vivid in Hα, and one imager mapped SII, Ha and OIII with 400, 300 and 320 minutes.
- Totals vary widely: one imager took 9.2 hours of 3-minute narrowband subs, another 65 hours with a dual-band filter from a Bortle 6 site.
- Best around August and September, peaking near 80° altitude from 50°N.
Facts
- Size
- 60′
- Magnitude
- —
- Coordinates
- RA 23h 16.1m, Dec +60° 2′
- Framing, APS-C
- 400–670 mm
- Framing, full frame
- 620–1030 mm
- Best months
- Aug, Sep
- Peak altitude
- 80° from 50°N, 65° from 35°N
Nearby
- H-NGC7510 · 49.7′ away