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Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1991-10-29 to 1991-10-30


This description was generated automatically using input from the Planetary Data System.

This data set includes full resolution electric and magnetic wave spectra obtained during a ~ 2-hour period of contiguous observations near the closest approach to Gaspra and a number of non-contiguous spectra taken prior and subsequent to closest approach. In addition waveform survey data (uncalibrated) and all instrument housekeeping data are included. The parameters provided for both the electric and magnetic field spectral data are uncalibrated data numbers. Software and calibration tables provided as part of this data set allow for fully calibrated data for the electric field measurements in raw data numbers, voltage at the antenna inputs (V), electric field (V/m), electric field spectral density (V**2/m**2/Hz), or power flux (W/m**2/Hz). The magnetic field measurements can be provided in units of magnetic field spectral density (nT**2/Hz). The sources of these data are the High Frequency Receiver, Sweep Frequency Receiver, and Spectrum Analyzer which make up the Low Rate Science portion of the PWS. During the included time interval, the instrument cycled between the electric and magnetic antennas for the Sweep Frequency Receiver and the Spectrum Analyzer. The High Frequency Receiver is always connected to the electric antenna. Hence, for the Sweep Frequency Receiver and the Spectrum Analyzer, the temporal resolution for electric measurements is basically one spectrum per 37.33 seconds. For the High Frequency Receiver, the time between spectra is 18.67 seconds. Note that the lowest 14 High Frequency Receiver channels are sampled twice per 18.67 seconds while the remaining channels are sampled only once. The four Spectrum Analyzer channels are each sampled 7 times in an 18.67 sec interval. The waveform survey data are generated by the wideband receiver portion of the Plasma Wave Instrument. These data are 4-bit measurements of the voltage across the preamplifier input at a rate of 201.6 k, 25.2 k or 3.2 k samples per second (for the 80 kHz, 10 kHz, and 1 kHz bandwidth modes, respectively) using either the electric dipole or magnetic search coil antennas. An automatic gain control receiver is used to set the gain at an optimum value so as to make the best use of the limited dynamic range afforded by the 4-bit analog-to-digital converter. In principle, it is possible to use the Automatic Gain Control (AGC) readout contained in the data set to calibrate this voltage, but this capability does not currently exist for this data set.

These data are available on-line from the Planetary Data System (PDS) at:

Alternate Names



  • Planetary Science: Fields and Particles

Additional Information



Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II



NameRoleOriginal AffiliationE-mail
Prof. Donald A. GurnettData ProviderUniversity of Iowa
Dr. William S. KurthGeneral ContactUniversity of
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