LANL/Magnetospheric Plasma KP Data Caveat

This file 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 preliminary and have not been checked in detail.

LANL/Synchronous Orbit Particle Analyzer KP Data Caveat

Electron, proton and helium measurements are taken every 160 ms from one of the three telescopes according to the following sequence: T1, T2, T3, T2, T1, T2 etc. Heavy ion data accumulated from each of the three telescopes again according to the timing and sequence above and summed for 10.24 seconds which is approximately one spacecraft rotation. SOPA Key Parameters are normally averaged over three telescopes for ~ 1 minute (6 - 10.24 second data accumulation cycles) giving an average over much of the sky. The time associated with each set of Key Parameters is determined by using the time (in minutes of the day) at the start of each data collection cycle as an index into an array of 1440 time slots dividing the day into 1440 one minute intervals. The time reported is the midpoint of each interval.

We provide six fluxes: Low energy Protons: 50 keV to 400 keV High energy Protons: 1.2 MeV to 5 MeV Low energy Electrons: 50 keV to 225 keV High energy Electrons: 315 keV to 1.5 MeV Helium : ~0.9 MeV to ~1.3 Mev Heavy Ions : ~5 MeV to ~15 MeV (includes carbon, nitrogen, and oxygen We also compute two electron temperatures and densities and two proton temperatures and densities. These are based on approximately the same energy ranges as the fluxes given in above and are determined for relativistic Maxwellian distributions.

Status of SOPA Instrument 1989-046: Operating normally as of 01-Feb-1993

Status of SOPA Instrument 1990-095: Loss of all ion data as of July 1992 All three thin, front, D1 detectors have failed, having become intolerably noisy. The net result of this failure is the complete loss of proton, helium, carbon, nitrogen, oxygen and other high Z Key Parameter data from the instrument. Since all three thick, back D2 detectors are still operating normally, the electron measurements remain only insignificantly affected.

Status of SOPA Instrument 1991-080: Operating normally as of 01-Feb-1993 with the following exception. Detector D1 on Telescope 2 is becoming noisy. This affects proton and ion data from that telescope. Bad data is disabled thru software in the ground processing and is NOT averaged into the Key parameter data. Therefore, the parameters given are good but do not cover the same percentage of the sky.

Data is flagged with a data quality flag as follows: +1 Data is Good 0 Data is Suspect -1 Data is Unusable LANL personnel should be contacted before using any data tagged as suspect.