THE CORONAVISER 



255 



millionths or approximately 6000 times as bright as the corona. On 

 very clear days the brightness was as low as 1250 millionths and this 

 limit may have been set by the scattered light from the telescope 

 parts, particularly the siderostat mirror, rather than the sky. The 



5500 6000 6500 

 WAVELENGTH IN ANGSTROMS 



Fig. 3 — Spectral characteristic of photo-cell. 



SWEEP CIRCUIT 



GENERATOR 

 AND TUNER 



AMPLIFIER CIRCUIT 



PHOTO-CELL 



Fig. 4 — The circuit diagram of the coronaviser. 



siderostat mirror had a surface of evaporated aluminum but by the 

 time the development of the equipment had progressed to the point 

 where useful images could be obtained, its surface had begun to show 

 blemishes. 



