M17 The Omega or Horseshoe Nebula in Sagittarius, an emission nebula

Contains open star cluster NGC6618 which illuminates the nebula.
BAA Picture of the Week 6-Aug-2017

HAG 24" RC reflector at f7.9. Moravian G4-9000 camera
3 x 5min each, LRGB,, FOV 33' x 33'
2017-07-31 @ 22:30 UT