Plasma Sheet Observations in 1-30keV Energetic Neutral Atoms

Philip Valek, Dave McComas, James Burch, Craig Pollock, Joerge-Micha Jahn, 
Herb Funsten, Ruth Skoug, Michelle Thomsen


The Medium Energy Neutral Atom (MENA) imager aboard the IMAGE spacecraft 
routinely observes the "bright" emissions from around the Earth.  Under proper 
conditions, MENA can also observe the "dim" emissions from the plasma sheet.  
In order to qualify these emissions, we first investigated the source of 
elevated backgrounds periodically observed by MENA.  We find that elevated 
background rates are well correlated with enhanced GOES-8 proton fluxes in the 
0.7-4 MeV range.  When these fluxes drop below ~10 cm-2 s sr MeV, MENA's count 
rates when looking away from the Earth nearly flatten out, indicating times 
when the dim ENA emissions are visible above the background.  MENA 
observations of the plasma sheet are correlated with observations of the Super 
Dense Plasma Sheet (SDPS) as seen by the  Magnetospheric Plasma Analyzer 
(MPA).  Observation of the plasma sheet by MENA are shown from intervals when 
SDPS are identified and when MENA has both a low background and is in a 
viewing geometry to look down tail.

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To be presented at the 2002 Spring A.G.U. Meeting, 
Washington, D.C., U.S.A., 28-31 May 2002