Canadian Network for Space Research/U. of Calgary Polar Cameras

The Polar Cameras are a pair of advanced all-sky imagers 
for airglow and auroral studies.  Each of the imagers has a fish-eye 
objective lens, telecentric fore-optics, a five-position filter wheel, 
and an unintensified CCD detector thermoelectrically cooled to below 
-40 C.  Such cooling, combined with advanced readout technology, 
provides extremely low-noise images.  Both imagers are controlled by 
a 80386-based PC which provides fully automatic and programmable turn-on 
and turn-off, 
data acquisition, and data archiving to 4mm DAT.  Each of the imagers 
and its electronics is sealed in an insulated enclosure purged with 
dry nitrogen, and is capable of operating outdoors continuously through 
the four-month-long polar night.

The imagers differ only in the filters through which they image the sky.  
In auroras the Polar Camera images the [OI] 630.0 nm line and the N2+ 
Meinel (2,0) band simultaneously, to allow diagnosis of the mean energy 
of the precipitating auroral electrons.  In high-altitude auroras the 
same information may be obtained from [OI] 630.0 nm and [OI] 557.7 nm 
emissions, which are also imaged simultaneously.  The Polar Camera also 
obtains simultaneous images of the near-IR OH airglow in two adjacent 
wavelength bands (829 nm and 835 nm), from which the temperature at the 
mesopause (~85 km altitude) can be deduced.  In addition to these features, 
the Polar Camera can image auroral emissions at 520.0 nm ([NI]) and 668 
nm (N2 1 Positive (5,2) band), and the background continuum emissions 
at 608 nm, 714 nm, and 820 nm.