This corona was photographed in December 2000 while camping at the El Tatio geyser field at 4300 meters elevation in the Chilean Andes. The corona radius is approximatly 50°. Blue inner disk extends to about 35° from the sun. In between the blue and red, a green band was seen visually, but it was not reproduced on film. Altocumulus clouds were developing from the stuff that made the corona. The corona may be related to the dust that is released in large amounts in the air from some mines in the area.
Cyan saturation was increased in the photo to make the inner blue disk better visible. Otherwise the photo is as scanned from the slide. See here for some more material. The degree grid is made with HaloSim by Les Cowley and Michael Schroeder.