All-Sky Optical Imager data, Arrival Heights, Scott Base, Antarctica

An All-sky Optical Imager was installed in January 1996 at Arrival Heights, Ross Island, Antarctica, to continuously record and analyse optical emissions associated with solar wind particle reactions in the upper atmosphere. The optical components were mounted on a frame suspended from the roof below an outside glass dome. The set up was moved once in January 2007 but maintaining annually. The optical imager can only be used when the sun is below the horizon for a reasonable part of the day. This occurs first in May. During May, June and July the camera records data whenever conditions (when there is no moon) allow the very low intensity optical phenomena to be observed and recorded. The All-Sky Optical Imager collects data annually and operates in concurrence with American collaborators. The camera consists of a fish-eye lens that provides an image that is separated into two wavelengths, 630nm and the other at 428.7nm that are focused onto an image intensifier tube and the output is scanned by a CCD TV camera. The solar wind particles are ionised particles expelled from the surface of the sun (composed of electrons and protons, the constituents of hydrogen and an extremely small number of heavier ions). Solar reactions produce solar winds which in turn depend on particle density and velocity, changing with the activity of the sun at the time of ejection. The solar wind continually varies in speed, density and direction when interacting with the Earth. Direct collisions of incoming particles with atoms and molecules in the upper atmosphere produce optical radiation (light) at wavelengths that identify the reaction.