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Local time dependences of oxygen ENA periodicities at Saturn
Author(s) -
Carbary J. F.,
Mitchell D. G.,
Brandt P. C.
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2014ja020214
Subject(s) - noon , saturn , local time , physics , dusk , latitude , astrophysics , midnight , longitude , atmospheric sciences , astronomy , environmental science , planet , mathematics , statistics
The periodicities of energetic neutral atoms (90–170 keV oxygens) at Saturn are determined by applying Lomb‐Scargle periodogram analyses to energetic neutral atom (ENA) fluxes observed in eight local time sectors of the equatorial plane between 5 and 15 R S (1 R S = 60,268 km). The analyses come from four long intervals (>180 days each) of high‐latitude viewing from 2007 to 2013 and represent an essentially global view of Saturn's periodicities. The periodograms display rich and complex structures in local time. Sectors near midnight generally exhibit the strongest periodicities (in terms of highest signal‐to‐noise ratios) and often show the dual or single periods of the Saturn kilometric radiation (SKR). Sectors near noon display single or multiple periodicities or none. Furthermore, dayside periods may be much shorter (~10.3 h) than SKR periods. Sectors near dawn or dusk display periodicities intermediate between midnight and noon or may show no periodicities whatsoever. These patterns of local time dependence do not remain constant from interval to interval.