Data Set Overview
=================
This data set contains the results for the Implanted Ion Sensor (IIS)
of the Johnstone Particle Analyser (JPA) instrument flown aboard the
GIOTTO spacecraft during its extended mission to fly by comet
P/Grigg-Skjellerup. The IIS instrument produced data in three modes
during the encountered, labelled as 'D4D', 'STC' and 'TOF'. The
files in this data set present the results obtained in those modes
in the form of flat ASCII files.
Parameters
==========
In each mode, the data recorded are a distribution of counts over an
integration period of 32 spins (Nominal spin rate is 4 seconds per
spin). The three modes are:
D4D Four-dimensional (full) resolution mode. Counts are binned
by polar angle, azimuthal angle, energy level and mass group.
TOF Time-of-Flight mode. All angular bins are combined; data are
binned by energy level and time of flight.
STC Start vs Start-Stop mode. In this mode, the number of impacts
triggering a START pulse, and the number triggering both a
START and STOP pulse (i.e., real events) are tabulated.
Note that since the processing program used the same output matrix for
all modes, dimension labels are sometimes misleading. Consult the
definitions in the PDS labels for clarification.
Processing
==========
These text files were produced by running the processing softare
designed for this purpose at Mullard Space Science Laboratory,
University College, London. No further data processing was performed
at the Small Bodies Node, apart from preparing the PDS labels.
The data were processed once, the parameters adjusted, and the
processing repeated. During the download of this second pass, two
files were lost: t1922205.txt and s1922205.txt. These files were
recovered from the first pass, with the loss of one data record at
the beginning of each file. The STC files were reformatted to a more
readable format from that of the second-pass output; and all files
had carriage-control characters added to end record.
Data
====
These data have been corrected for know telemetry glitches and hardware
failures, but are otherwise unprocessed. They were used to generate
the JPA part of the results listed in the JPAMG data set, which merges
the analyzed results of these data with results from the magnetometer
experiment. The files are designed for visual inspection, rather than
for input to another program.
Media/Format
============
The data set is available as part of the GEM CDROM collection,
published by the PDS Small Bodies Node.