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Fast photometry of flickering in discrete auroral arcs
Author(s) -
McHarg Matthew G.,
Hampton Don L.,
StenbaekNielsen Hans C.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/98gl01972
Subject(s) - photometry (optics) , flicker , physics , narrowband , intensity (physics) , optics , broadband , astrophysics , stars , electrical engineering , engineering
We present high speed photometric measurements of the auroral intensity of flickering aurora. These measurements reveal the existence of intensity modulations in the discrete aurora above the Nyquist frequency of standard 30 frame per second TV cameras. The intensity fluctuations observed are primarily below 80 Hz, although frequencies up to 180 Hz have been detected. Changes in the spectral characteristics from essentially band‐limited to broadband intensity fluctuations and then to narrowband fluctuations are seen in individual discrete arcs within a few minutes. The center frequency of the observed fluctuations also change during this period. Data obtained from a standard narrow field TV camera observing the same arc show that only the low ( ≈ 10 Hertz) narrowband modulations would be considered standard flickering aurora.