NGC 6888 "Crescent Nebula" in HOO (cropped)
NGC 6888 of Crescent Nebula lies in Cygnus 5,000 light-yease from Earth. This is a cropped HOO image photographed through 3 nm Hydrogen-alpha and Oxygen-III filters. It is a joint project of James Foster and me.
file: NGC6888-C11HOO-a2cr3.jpg
Click here for full resolution photo

Photographic Data
telescope:
Celestron 11-inch (black tube) SCT with Starizona 0.75X reducer/flattener
Aperture: 2,794 mm (11-inches)
Focal length = 2,095 mm
Focal ratio: f/7.5

mount:
Astro-Physics 1200 GTO

guiding:
Off-axis with ZWO ASI120MM mini camera

imaging camera:
ZWO ASI6200MM-Pro monochrome camera
(cropped image)

exposure:
3 nm Hydrogen-alpha for 350 minutes and 3 nm Oxygen-III for 460 minutes.
Total exposure time: 810 minutes or 13.5 hours

photographic site:
James Foster observatory at Frazier Park California
(Bortle 4 at 5,500 ft elevstion)