12-Hour IMP 6 Color Energy-Time Plasma Spectrograms, Digital Images 
in GIF Format

NSSDC ID: SPMS-00733          (Old NSSDC ID: 71-019A-05B)

Description

This data set consists of GIF images produced at NSSDC by scanning 140 experimenter-supplied 
35-mm slides of full-color E-t (energy-time) spectrograms of plasma measurements with the 
University of Iowa instrument on board IMP 6 (IMP-I). The instrument consisted of a LEPEDEA 
(Low Energy Proton and Electron Differential Energy Analyzer) and an EON type 213 directional 
GM counter. The GM detector was used to measure the intensity of electrons of energies greater 
than 45 keV and protons of energies greater than 500 keV and to provide background measurements 
for the LEPEDEA.

The spectrograms display the color-coded detector responses to proton intensities as functions 
of energy (ordinate) from 40 to 1.E5 eV and time (abscissa) for four sectors in the spin plane
of the instrument. Also shown are the responses of the GM detector for the same four sectors, 
and the response of the LEPEDEA electron channels, which are averaged over the directions of the 
fields of view. Each slide covers twelve hours.

The color response was modified to make the four sectors of GM responses more readily visible and
to improve the visibility of the color-coded intensities.

The color slides which were scanned at NSSDC to make this digital data set comprise data set 
SPMS-00730 (old ID 71-019A-05A).