The instrument data consists of cataloging information, instrument status , instrument readings at time of impact, and classification information. The instrument readings are the amplitude codes of the detectors on-board the instrument, the rise time integer codes of the charge level rise times of the detectors, the integer code representing the difference in starting times of the ion signal and the electron signal, and coincidences between the electron and ion signals, and between the ion and channeltron signals. The classification information is used to assist in classifying an event into probable impact and non-impact categories. Since the composition of particles striking the Galileo spacecraft is unknown, logarithmic averages of the above values are used to infer the particle speed and mass from the instrumental measurements. The data contain different levels of processing.
Some processing is done at the time of the impact observation.
This processing categorizes the detector responses to transmit the data efficiently back to Earth. Data received on Earth is given as an integer code. These integer codes can, for example, represent ranges of values, or can be a classification determined from other integer codes. On Earth, these integer codes are then fit to calibration curves to determine the speed and mass of the impacting particle. This data set contains the information from the spacecraft instrument as received on Earth, information about the location and pointing direction of the spacecraft, and the physcial properties determined from the data analysis.