'The ISEE-1 and -2 Plasma Wave Investigation' D. A. Gurnett, F. L. Scarf, R. W. Fredricks, and E. J. Smith, IEEE Transactions on Geoscience Electronics, Vol. GE-16, p. 225-230, 1978. The International Sun-Earth Explorer (ISEE) Program consisted of three satellites intended to study the Earth's magnetosphere and the solar wind. ISEE-1 and ISEE-2 were launched on October 22, 1977 into highly elliptical geocentric orbits. The satellites passed through the magnetosphere and into the magnetosheath during each orbit. ISEE-3 was launched on August 12, 1978 and subsequently inserted into a 'halo orbit' about the the libration point situated about 240 earth radii (Re) upstream between the earth and the sun. Plasma passing this point arrives at the Earth about one hour later where it may cause changes that can be observed by ISEE 1 and ISEE-2. These two spacecraft, separated by a variable distance and with similar instrument complements, were intended to resolve the space-time ambiguity associated with measurements by a single spacecraft on thin boundaries which may be in motion such as the bow shock and the magnetopause. ISEE-1 and ISEE-3 were the principal U. S. contributions to the International Magnetospheric Study. ISEE-2 was built and managed by the European Space Agency. In September 1982 ISEE-3 was diverted from its 'halo orbit' to explore the earth's deep tail region through much of 1983 on its way to an encounter with the comet Giacobini Zinner in September 1985. ISEE-1 had a complement of thirteen experiments to measure the waves, fields, plasma, and particles. The University of Iowa Plasma Wave Instrument (PWI) was one of these thirteen. The ISEE-1 plasma waves instrument provided a comprehensive determination of wave characteristics over a broad frequency range, including high-frequency resolution spectrum scans, simultaneous high-time resolution electric and magnetic frequency spectrum measurements, wave normal and Poynting flux measurements, and wide-band waveform measurements. PWI sampled the environment using three electric dipole antennas with lengths of 215, 73.5, and 0.61 meters for electric-field measurements, and a triaxial search coil antenna with three 16-in high permeability mu-metal cores each wound with 10,000 turns of wire and a preamplifier for magnetic-field measurements. The experiment's main electronics consisted of four main elements: 1) a narrow-band sweep frequency receiver, 2) a pair of high time resolution spectrum analyzers, 3) a wave normal analyzer, and 4) an analog waveform receiver (also called a wide-band receiver). These elements could be electrically connected to the six antennas in various combinations in flight. Data for this file originate with the spectrum analyzers. The PWI Spectrum Analyzers were designed to provide high time resolution spectrum measurements for resolving wave emissions that are bursty or of a nonlinear nature. The pair consisted of a 20-channel analyzer covering the range from 5.62 Hz to 311 kHz, and a 14-channel analyzer covering the range from 5.62 Hz to 10 kHz. These analyzers have a relatively coarse frequency resolution, with four frequency channels per decade and bandwidths of +/-15 percent up to 10 kHz and +/-7.5 percent for 10 kHz and above. The center frequencies and bandwidths of the 20- and 14-channel analyzers are identical. The 20-channel analyzer was nominally intended for electric field measurements (which extend up to higher frequencies than the magnetic measurements), and the 14-channel analyzer was nominally intended for magnetic field measurements. All channels are sampled simultaneously so that electric-to-magnetic field ratios could be accurately determined. For a detailed description of the Plasma Wave Instrument, the reader is referred to the IEEE Geoscience Electronics reference above. A common acronym for the plasma waves instrument in older documentation is GUM, which stands for for Gurnett Mother. Since this acronym is not easily recognizable by the space physics community and since no official acronym is provided in the instrument paper, the more common short hand 'PWI' is used to refer to the Plasma Wave Instrument in this archive.

Channel Frequency Centers, 20 (5.62 Hz to 311,000 Hz). These are the frequency channels for all 20 of the spectrum analyzer bands. In instances where data are collected via the 14-channel analyzer, the upper 6 wave power measurements will contain fill values.

Spacecraft Event Time in UTC for the start of an SA measurement.

Spin Plane E-Field Spectra, 215 meter long-wire antenna. These data are collected primarily via the fine wire electric dipole antenna which had a tip to tip length of 215 meters. The Ev antenna was used to collect over 99% of the E-field measurements obtained by the PWI. Most of the time (98.3%) these data were collected via the ESA (Electric Spectrum Analyzer). Though a small fraction of the data are from the MSA (Magnetic Spectrum Analyzer). The two analyzers have almost identical channel centers and bandwidths, except that ESA has 6 more bands above the highest band of the MSA. When the MSA is used to read an electric antenna, the upper 6 bands are marked with fill data. This antenna was shared with the Heppner DC electric-field experiment. The 'E_Quality' variable flags times when known spacecraft noise sources are present in the E-field data.

Spin Plane E-Field Spectra, 73.5 meter two-sphere antenna. Less that 0.5% of electric spectra in this data set were collected via the Eu antenna. This variable is almost always empty. The Eu sensor is a two-sphere electric antenna which had a sphere-to-sphere separation of 73.5 meters. The spheres on the u-axis have a diameter of 8.0 cm and each contains a high-impedance preamplifier which provides signals to the main electronics box which contained the spectrum analyzers. This antenna was shared with the Mozer quasi-static electric-field instrument. Consult the 'E_Quality' variable for issues regarding Ev_Spectra values.

Integer combining all E-antenna data quality flags, 0 = no issues detected. A bitwise OR'ing of all known issue values for this record. The following issue values are defined. (0x4: MOZER) if this flag is present then the Quasi-static Electric Fields instrument (F. S. Mozer) is performing a bias sweep, (0x8: HARVEY) identifies possible interference that occurs when the Plasma Density instrument (C. C. Harvey) injects signals on either of the long electric dipole antennas.

Spin Axis B-Field Spectra, Bz search coil. These data are collected via the z-axis Magnetic Search Coil (Bz) which has an upper cutoff frequency of 10 kHz. It's constructed of a 16 inch mu-metal core and wound with 10000 turns wire. Almost 99% of all magnetic field measurements from the PWI were collected via the Bz search coil. NOTE: When they are present at all, the upper 6 frequency indices contain data collected above the search coil's upper cutoff frequency. Though these data are included for completeness, all samples above 10 kHz are not calibrated data and should be used with caution. See the 'B_Quality' variable and the 'Quality_note' for issues regarding Bz_Spectra

Spin Plane B-Field Spectra, Bv search coil. These data were collected via the V-axis Magnetic Search Coil (Bv). This coil had the same physical properties as the Bz coil but was mounted perpendicular to the Bz coil. The Bv coil axis pointed along the V direction, which is within the spacecraft spin plane. This variable is usually empty. Less than 2.5% of magnetic spectra were collected via this search coil. See the 'B_Quality' variable and the 'Quality_note' for issues regarding Bv_Spectra.

Spin Plane B-Field Spectra, Bu search coil. These data were collected via the U-axis Magnetic Search Coil (Bu). This coil had the same physical properties as the Bv coil but was mounted perpendicular to both the Bz and Bv coils. The Bu coil axis pointed along the U direction, which is also within the spacecraft spin plane. This variable is almost always empty. Less than 0.1% of magnetic spectra were collected via this search coil. See the 'B_Quality' variable and the 'Quality_note' for issues regarding Bu_Spectra.

Integer combining all data B search coil quality flags, 0 = no issues detected. A bitwise OR'ing of all known issue values for this record. The following issue values are defined. (0x1: SCAN) if this flag is present then the Medium Energy Particles instrument's (D. J. Williams) scan platform is in operation, (0x2: Z-MEAS) if this flag is present internally generated signals are being applied to the search coil antennas.