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Giotto Particulate Impact Analyzer Observations near Comet Halley


Abstract: The PIA data was acquired in four modes of data compression, termed mode 0 (the least compressed), and modes 1, 2, and 3, each with increasing degrees of compression. With each spectrum are a PIA assigned sequence number and event numbers, a unique ID-number, instrument settings, and the relative approach time. The PIA time is a 16-bit counter that starts with zero after switch-on. As the Spacecraft Time Signal (STS) is used to reset the internal PIA time counter, the TIM highest possible value is 48960 counts. STS-pulses are given after the transimssion of 256 formats. This results for format F1/F2 and high bitrate (46080 bps) in 5802.67 s. (= 256 formats * 64 frames * 2040 bytes * 8 bit/byte/46080 bps) The time resolution is DTIM = 1/ (138240 HZ /2**14 ) = 0.1185 s. Each STS defines the time for an event with TIM = 0. Therefore, SCET = GRT(STS) + (TIM * DTIM) - propogation delay (8:00.1 sec). where SCET = Spacecraft Event Time, GRT = Ground Reception Time.

GIO-C-PIA-3-RDR-HALLEY-V1.0 Browse Download (13.7 MB)

Citation to use when referencing this data set: "Kissel, J., and A.C. Raugh, GIOTTO PARTICLE IMPACT ANALYZER DUST MASS SPECTRA V1.0, GIO-C-PIA-3-RDR-HALLEY-V1.0, NASA Planetary Data System, 1990."

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