The Keyhole Nebula is a portion of the Carina Nebula.
(The Round object Seen here a little lower from the center)
The name was given to it by John Herschel in the 19th century.
The Keyhole Nebula is actually a much smaller and darker cloud of cold molecules and dust,
containing bright filaments of hot, fluorescing gas, silhouetted against the much brighter background nebula.
The diameter of the Keyhole structure is approximately 7 light years (WIKI)

Imaged with the 16" f3.75 Dream Astrograph.
Apogee Alta U-16M camera.
HA-O3-LRGB image
R-HA-O3 (mapped as RGB)
Ha - 40 min ,O3 - 30 min
Luminance - 20 minutes , RGB 10 minutes each

(Total of 2 HRS)

Imaged from Tivoli farm in Namibia June 2012.