Data Set Overview : The energetic particle observations presented here were made with the University of Maryland/Max-Planck-Institut ULECA sensor on the International Cometary Explorer encounter with comet Giacobini-Zinner in Sept, 1985. The ULECA sensor is well suited for these studies since its energy range (30-180 keV) is close to that of water group ions, whose initial energy of 20 keV in the solar wind (SW) frame (for V (SW) : 450 km s** -1) corresponds to 0-80 keV in the spacecraft frame before acceleration to higher energies in the turbulence associated with the comet. The instrument uses a multislit collimator, an electrostatic deflection system, and an array of silicon solid-state detectors to identify particle energy, and energy per charge, from which the charge state may be derived. A general description of the ULECA sensor has been published by Hovestadt et al. (1978).  The ULECA sensor view angle extends +/- 3O degree off the ecliptic plane; the spacecraft rotation scans the ecliptic, with the count rates divided into eight sectors, numbered 0-7, with sector 5 centered on the solar direction. In the NSSDC submission, data are used from different groups of sectors. The nomenclature used is as follows: solar sector means data from sector 5 only; solar sectors means data from sectors 4, 5, and 6; and 'antisolar sectors' means data from sectors 0, 1, and 2.  The ULECA instrument response and the data analysis are sensitive to the mass of the incident ions, but they do not measure this mass directly. In our earlier work (Ipavich et al., 1986) it was shown that the particles in our energy range had a mass of at least 12 amu. At plasma energies, (Ogilvie et al. 1986) showed that H,O + ions were dominant among the singly charged ions, which is consistent Halley data. For this case the three energy channels of ULECA for singly charged particles (Mll, M21, and M31) have mean energies of 35, 70, and 150 keV,, respectively. The energy resolution full widths at half maximum, delta E/E, are 20, 27, and 37%, respectively. The efficiencies for detec- tion of water group ions were determined by a detailed analysis which included evaluation of thresholds, energy defect, and noise width, for each detector. The resulting efficiencies are 0.95, 2.6, and 3.4% for the M11, M21, and M31 channels, respectively (Ipavich et al., 1986).   Data : At encounter the ICE spacecraft traversed the cometary region along a path almost perpendicular to the ecliptic, moving from south to north. The relative speed of the spacecraft to the comet was -21 km s-1. The submitted data is high time resolution (256 s) summary records (count rates) for the period centered on closest approach, 1102 UT on September 11, 1985.  The M21 count rate, however, was contaminated by cross talk with another detector in the instrument. Although large, this cross talk was not dependent on the pointing direction of the spacecraft, making it possible to correct M21 by assum- ing that all counts in the antisolar sectors.were background and then subtracting this level from the measured counts in the solar sectors. The M21 data archived were not corrected in this manner (see Tan et al 1990), and have a substantial background count.  The counts rates for both sectored and non-sectored data have been included to capture all the relevant rate designations (Table 1 from Hovestadt et al. 1978). Sectored data for format C (M 11, M13, M31, M22, M21) and format E (L1, L2, E1, M12) are for 8 recorded sectors. Non-sectored data for format E (E1, E2, E3, E4, M11, M12, M13, M31, M22, M23, M21, M32, M33, MB1, MB2, MB3, MP12, MP1L, MP2L, MP3L) are also included.

Review :  PDS Peer review was held in fall 1998.   Data Coverage and Quality :  The original data was converted from binary files to ASCII tables at the NSSDC. Data covered a time period from Sept 8-22 but only the relevant period (Tan et al. 1993) for Sept 9-13 is included.