Finding
The photometric method for determining auroral activity is not commonly used, despite the inaccuracies of visually estimated total intensity due to individual differences in observers and difficulty in estimating intensity-variations.
Paper
The determination of auroral activity by a photometric method
Citations: 0
Full textAbstract
In the majority of records of auroral activity the total intensity has been estimated visually and the results expressed in international coefficients ]see 1 of ”References“ at end of paper[. This is a useful method but is liable to inaccuracies due to individual differences in observers and to the difficulty of forming any precise estimate of intensity-variations when these are accompanied by changes in color and by a movement of the luminous regions. In a few cases objective records of activity have been made. The French Polar-Year Party at Scoresby Sound used an electrical device for measuring intensity [2]. It appeared to be very satisfactory, even detecting auroras during foggy weather. The records show that the luminous intensity may vary in the ratio 1:1000. The method does not seem, however, to be in general use. Continuous photographic recording of the intensity of various spectral lines has also been used [3]. The plates were exposed for a constant interval and the developed image-densities compared. In this way a curve of average activity during successive intervals of time can be plotted.
Authors
L. B. Snoody, V. C. Snoody
Journal
Eos, Transactions American Geophysical Union