|Object name:||Constellation:||Coordinates:||Apparent size:||Visual brightness:|
|NGC 6888||Cygnus||20h12m / +38°21'||18' x 12'||7.4 mag|
The emission nebula NGC 6888 ("Crescent Nebula", Caldwell 27, Sharpless 105) in the constellation Cygnus. NGC 6888 was formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with a slower moving wind ejected by the star when it became a red giant some 250,000-400,000 years ago. NGC 6888 is about 5,000 light-years from Earth and was discovered by German-born British astronomer Frederick William Herschel in 1792 (source: Wikipedia).
Twenty-six 3-minute exposures (78 minutes total exposure) at gain 100 taken on August 2, 2022, were added for this shot with the Astro Pixel Processor (APP) software and the final image processing was done in Photoshop. Darks, flats, bias and dark flats were used.
Equipment: Cooled ASI 2600MC Pro camera, TeleVue Paracorr Type II coma corrector, 16" f/4.5 "Ninja" dobsonian telescope riding on a dual-axis Tom Osypowski equatorial platform, Lacerta MGEN autoguider, Lacerta off axis system.