This directory provides access to hourly resolution energetic proton and alpha particle data from the JHU/APL Solar Proton Monitoring Experiment (SPME) on the IMP 4 or IMP 5 spacecraft. IMP's 4 and 5 are also known as IMP's F and G. (Data for each spacecraft are in spacecraft-specific directories that share this readme file.) The data correspond to count rates (counts/sec) in the five "channels" 1. protons (mainly), >60 MeV 2. protons (mainly), >30 MeV 3. protons (mainly), >10 MeV 4. protons (mainly), 1-10 MeV 5. alpha particles (mainly), 1-10 MeV Geometric factors for these channels are 6.28, 6.28, 0.80, 1.7 and 1.7 cm**2 ster, respectively. The data were provided by JHU/APL to NSSDC many years ago on magnetic tape, in IBM binary format. ASCII versions of the data were created at NSSDC in 2003 for convenient researcher usability. Fluxes computed from the rates of channels and the geometric factors were added to the OMNI data set for 1967-1972. Each hourly record has time, spacecraft location, five count rates and, for each rate, the number of samples. For days with any data, there are 26 records. For days with no data, there are no records. The 25th and 26th records are used when partial averages were computed for a given hour because a ~4 day orbit ended, and another started, during that hour. The data files are specific to a given year. For IMP 4, the files are for 1967 (start day = 150), 1968 and 1969 (end day = 123). For IMP 5, the files are for 1969 (start day = 172), 1970, 1971 and 1972 (end day = 358). The detailed format of each record: 1 I4 Year (1967, ...) 2 I4 Day of year (1, 2 ... 365 or 366) 3 I3 Hour of day (0 ... 23) 4 F9.3 Geocentric longitude of spacecraft (-180 to +180) 5 F9.3 Geocentric latitude of spacecraft (-90 to +90) 6 F8.0 Geocentric distance of spacecraft (km) 7 E10.3 Average counts rate for Channel 1 (>60 MeV) 8 I4 Number of samples in average (-1: interpolated value) 9-16 same as 7,8 for Channels 2-5 respectively 17 I3 First minute of hour for which there was data 18 I2 Data flag * * The data flag has the following meanings 0 No data for this hour 1 Data for this hour, in middle of orbit 2 Data for this hour, first hour of orbit, unaveraged w. prior orbit 3 Data for this hour, last hour or orbit, unaveraged w. next orbit 4. Data for this hour, weighted average of two orbits' values cf. Williams and Bostrom, J. Geophys. Res., 74, 3019, 1969. for an discussion of the IMP F SPME instrument and early science results. Related data and directories: SPDF Data and Orbits Services -------------- SPDF Contact: Natalia Papitashvili , Please acknowledge NASA's Space Physics Data Facility for data usage. Authorizing NASA Official: Dr. R.E. McGuire, Head, SPDF, NASA Goddard Space Flight Center 301-286-7794, e-mail: Robert.E.McGuire@nasa.gov -----------------------------------------------------------------------