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1) LANL02A MPA at 87 sec Resolution in Spacecraft Coordinates maxmize
Resource ID:spase://VMO/NumericalData/LANL/2002/MPA/PT87S
Start:2003-10-29 00:00:00 Observatory:LANL2002 Cadence:87 seconds
Stop:2008-01-03 23:59:59 Instrument:LANL2002 Magnetospheric Plasma Analyzer Resource:NumericalData
The LANL 02A MPA data set contains numerical moments computed from measurements of the Los Alamos Magnetospheric Plasma Analyzer (MPA) [Bame et al., Rev. Sci. Inst., in press 1993]. The moments are presented in s/c coordinates: the z-axis is aligned with the spin axis, which points radially toward the center of the Earth; the x-axis is in the plane containing the spacecraft spin axis and the spin axis of the Earth, with +X generally northward; and the y-axis points generally eastward. Polar angles are measured relative to the spin axis (+Z), and azimuthal angles are measured around the z-axis, with zero along the +X direction. The moments are computed for three 'species': lop (low-ener. ions, ~1eV/e-~130eV/e); hip (hi-ener. ions, ~130eV/e-~45keV/e); alle (electrons, ~30eV - ~45keV ). The electron measurements are obtained 21.5 secs after the ion measurements. Epoch is the measurement time appropriate for the ions. The moments are computed after the fluxes are corrected for background and s/c potential. Algorithms for these corrections are relatively unsophisticated, so the moments are suspect during times of high background and/or high spacecraft potential. Because the determined spacecraft potential is not very precise, the magnitude of the low-energy ion flow velocity is probably not accurate, but the flow direction is well determined. Tperp and Tpara are obtained from diagonalization of the 3-dimensional temperature matrix, with the parallel direction assigned to the eigenvalue which is most different from the other two. The corresponding eigenvector is the symmetry axis of the distribution and should be equivalent to the magnetic field direction. The eigenvalue ratio Tperp/Tmid, which is provided for each species, is a measure of the symmetry of the distribution and should be ~1.0 for a good determination. Several of the parameters have a fairly high daily dynamic range and for survey purposes are best displayed logarithmically. These parameters are indicated by non-zero 'SCALEMIN' values in this file. A quality flag value of 1 indicates that the values are suspect because of unreliable location info.

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