NASA/Goddard Space Flight Center, Greenbelt, MD

This document describes the magnetic field experiment data processing systems for Explorers 47 and 50 that have been written to run on the GSFC, Science Directorate IBM 360 computers under IBM 360/OS release 21.7. It presents the overall scheme and rationale for these systems, defines the various programming levels, and describes the types and formats of output products. The program modules employed in the principal part of the system, Phase I, are explained in detail. The Phase I program converts the raw X, Y, Z sensor data as received on the experimenter tape into useful detail vector measurements and averages of the observed magnetic field in physical units. The other program Phases (ZERO, II, and III) are briefly described. These perform the following functions: ZERO provides calibration parameter values to Phase I, Phase II transforms the data from spacecraft coordinates to physically useful coordinate systems (solar ecliptic and solar magnetospheric) and produces hourly average cards, and Phase III yields detail data products in the form of plots and numerical listings. The combined system can provide data with the following time bases: detail (40 msec), 320 msec, 1.28 sec averages, 15.36 sec averages, multiples of 15.36 sec averages (by non-production program), and hourly averages. Data products in most cases are in the form of microfilm and magnetic tape. It is expected that this document will be of particular interest to scientists who use the Explorer 47 and/or 50 magnetic field data for the dual reasons of its providing (1) a description of the available forms of data and (2) a thorough explanation of how those data were produced. Also it might be of value as a guide to future programmers in the business of developing similar data processing systems, especially those systems able to handle data that are efficiently compacted by an onboard processor.

NASA-GSFC, X-694-76-158, Greenbelt, MD, Aug. 1976