L O W E N E R G Y P A R T I C L E S D A T A S E T 1. INTRODUCTION This data set contains fluxes and pitch angles (relative to measured magnetic field) of protons and electrons as measured in the lower half of the energy steps of the electrostatic analyzers, that is, at "<10 ev," 40 eV and 0.76 keV, 60 eV and 1.2 keV, and 100 eV and 1.8 keV. The indicated pairings correspond to simultaneous measurements in the low and medium energy analyzers. Time resolution is variable according to the memory mode being used at any time, ranging between 10 msec and 2.56 sec. Each data file corresponds to one memory readout, and typically consists of a few continuous-data segments. The first several records in each file constitute a header giving the time spans of the segments, the energy step, and other common information. The data records, in ASCII, also contain spacecraft position data. Time span of data set: 81-10-01 - 82-03-01 Time span for every file is given in "PARTICLE.TAB" file 2. SHORT DESCRIPTION OF INSTUMENT Particle detector RIEP-2802 was developed and built in Russia. It is 4-channel electrostatic spectrometer with spectral resolution (deltaE)/E ~ 0.2. The aperture angle was 0.036 sterad, geometric factors from 0.092 to 0.089 cmsq x sterad for different units. Two detector channels were for electrons, two channels for ions, all working in parallel. Among 8 energy steps possible only four were used in the seances presented below. They are identified in the heading of respective data column in each data file by the particles' central energy for each of the 4 detectors (NSTEP ranging from 0 to 3, see Table 2.1). For a detailed description see Galperin et al., Annales de Geophysique, v.38, N 5, p. 583, 1982. The Table 2.1. gives the respective central energies for these energy steps (NSTEP): Table 2.1. ----------------------------------------------------------------- NSTEP: Low energy : Low energy : Medium energy : Medium energy :electrons (eV): ions (eV) : electrons(keV) : ions (keV) ----------------------------------------------------------------- 0 <10 <10 <0.01 <0.01 1 40 40 0.76 0.76 2 60 60 1.20 1.20 3 100 100 1.80 1.80 ----------------------------------------------------------------- Note: NSTEP for every file is given in accompaning "PARTICLE.TAB" file. In the data files the values of the particle number flux is given in the data columns in units: particles per square cm per second per steradian per keV. Also given are the NSTEP code (in most of the seances, but not always, unchanged during a telemetry mode within a seance), and pitch-angle (angle between the local magnetic field direction and the particle velocity along a particular detector axis) for the registered electrons (ae) and ions (ie). These angles are evaluated from the onboard magnetometer data. Please, note that in a data file the first 1-7 rows usually give spurious data due to telemetry and instrument switched and decoding programs adjustments, AND THUS MUST BE DISCARDED. Besides, the locations of the typical particle precipitation boundaries deduced from the above channels and other particle detectors onboard, together with their INVARIANT LATITUDE/MAGNETIC LOCAL TIME, and definitions of the boundaries, are given in the separate file PRECBORD.TXT. 3. FILES AND FORMAT DESCRIPTION 3.1. Name of files The filename of data files contains the number of the memory readout seance followed by the letters "a3k". It has ".dat" exrention. Each data file has a header and number of data records. Logical data record -131 bytes +Cr/LF 3.2. Record format description WORD ASCII MEANING UNITS/COMMENTS 1 I4 Hour (0-23) 2 I3 Minute (0-59) 3 I3 Second (0-59) 4 I4 Millisecond 5 E12.3 Number flux, low energy electrons number/cmsq sec sr keV 6 E10.3 Number flux, low energy ions number/cmsq sec sr keV 7 E10.3 Number flux, medium energy electrons number/cmsq sec sr keV 8 E10.3 Number flux, medium energy ions number/cmsq sec sr keV 9 F6.0 Pitch-angle ae between magnetic Degrees, 0-180 field and mean electron velocity (downward: 0 in Northern Hemisphere, 180 in Southern Hemisphere) 10 F6.0 Pitch-angle ai between magnetic Degrees, 0-180 field and mean ion velocity (downward: 0 in Northern Hemisphere, 180 in Southern Hemisphere) 11 F8.1 Altitude km 12 F8.2 Geographic Latitude of the Degrees, +/-90 Spacecraft 13 F8.2 Geographic Longitude of the Degrees, 0-360 Spacecraft 14 F8.2 L, McIlwain's Invariant Magnetic Earth's Radii Drift Shell Parameter 15 F8.2 L0, Invariant Latitude Degrees, +/-90 L0=arc cos (sqrt(1/L)) 16 F7.2 MLT, Magnetic Local Time Hours.decimal hours (for centered dipole field) 17 F8.3 BMAG, Module of IGRF80 Magnetic MilliGauss Field (1 milliGauss=100nT) 18 F8.2 ZSUN, Solar Zenith Angle Degrees, 0-180 --------------------------------------------------------------------------- The parameters 8-15 were calculated with the CADR4 program developed in IKI for orbital and geophysical reference information for near-Earth satellites (Galperin et al., Preprint IKI (in Russian), Pr 544, 1980). 3.3. STRUCTURE OF A HEADER The header starts with a title: "PASSPORT FOR THE SEANCE S-XXXX, ARCAD-3". It gives (in place of XXXX) the number of the memory readout telemetry seance and the time intervals of the data recording. The first header text paragraph starts with a row "THE NUMBER OF THE TIME INTERVALS - YY". It gives (instead of YY) the number of uninterrupted memory recordings, each one in a particular memory mode ZAP (described in GENERAL.TXT). Each such recording is described as a line in the "PASSPORT...". Within a data file it corresponds to a number of lines each describing a "measurement point" by a line of the data. The number of measurement "points" (from the start to the end of each recording) is shown in two first columns of each line, the next columns give the date (dd.mm.yy) and the UT time (hh.mm.ss.mss) of the start of the interval, then the same for the end of an interval. The before last column of a passport row gives the DT - a data time step in milliseconds (mss), and the last column gives the memory mode ZAP (1-4). In the second heading paragraph, a reminder is given that the first rows (up to 7) with the data in each time/ZAP interval may be false due to telemetry switches, etc., AND THUS MUST BE DISCARDED. The third text paragraph in a file heading contains a reminder of the relevant data contained in the files and the units of the particle number flux: particles per cm^2 per sec per ster per keV. The "NSTEP=X" gives (instead of X) the energy step number during this time interval, the NSTEP, as described in the Table 2.1. above. The NX=ZZZZZ - gives (by ZZZZZ) the total quantity of the rows in the data file, or the number of the measurement points registered. Some of them can be erroneous due to telemetry noise, so the real quantity of the rows can be lower, or equal, to the NX quantity. The headings of each data column within a data file are provided, which contain the meaning of the data in the column (see Format Description above). As the date of measurements in a data file for each time interval is given in the "PASSPORT OF THE SEANCE", it is not repeated in the data rows, and only the UT is given. ___________________________________