Summary of the Lunar Prospector Spectrometers Gamma-ray and Neutron Time-series Submission to the Planetary Data System David J. Lawrence(1), Sylvestre Maurice(2), William C. Feldman(1), Richard C. Elphic(1), Olivier Gasnault(2) (1)Los Alamos National Laboratory, Los Alamos, NM USA (2)Observatoire Midi-Pyrenees, Toulouse, France 1. Introduction This document summarizes the submission of gamma-ray and neutron time-series data from the Lunar Prospector mission. Specifically, these data consist of fully corrected 32-second data accumulations from the Lunar Prospector Gamma-ray and Neutron Spectrometers (LP-NS, LP-GRS). Full descriptions of these data products and reduction procedures are given by Lawrence et al. [2003] and Maurice et al. [2003]. A detailed instrument description for the Lunar Prospector Spectrometers is given by Feldman et al. [2003]. The remaining portion of this document describes the file structure and contents of the submitted data. 2. LP-GRS Data Products 2.1 Naming Convention for LP-GRS Files Data from the LP-GRS are separated into files containing one day's worth of data. The datafiles contain binary data and are named with the following convention: yyyy_doy_grs.bin, where * yyyy gives the year the data was taken (either 1998 or 1999) * doy gives the day of year the data was taken (values from 001 to 365 are valid). For example, gamma-ray data collected on February 1, 1998 will be in the file named 1998_032_grs.bin. Auxiliary files, named yyyy_doy_grs.txt, contain supplementary information about the files such as the date and time the data were processed and written into binary files. 2.2. Contents of LP-GRS Files The reduction of LP-GRS time-series data are described in Lawrence et al., [2003] and does not need to be repeated here. Table 1 lists the contents of each daily file and how these data are formatted. The first four bytes are a value of type long that give the total number of samples, named num, in each file. Following the first four bytes are nine data products. The first two products are the 512 element accepted and rejected gamma-ray spectra. Following the spectra are the measured deadtime, overload, and LP-GRS temperature. Finally, the spacecraft time, height, latitude, and longitude are given. This sequence of eight data products repeats num times until the end of the file. The total size of each file should be num*(2*512 + 7)*4 + 4 = num*4124+4 bytes. Table 1: Contents of the LP-GRS binary timeseries files. Product Variable Data Total Total Start name name * type bytes items byte Number of samples num long 4 1 1 Accepted spectra acc1[512] float 2048 512 5 Rejected spectra rej1[512] float 2048 512 2053 Deadtime deadtime1 float 4 1 4101 Overload overload1 float 4 1 4105 GRS Temperature grstemp1 float 4 1 4109 Earth receive time ert1 float 4 1 4113 Spacecraft height hgt1 float 4 1 4117 Spacecraft latitude lat1 float 4 1 4121 Spacecraft longitude lon1 float 4 1 4125 Accepted spectra acc2[512] float 2048 512 4129 Rejected spectra rej2[512] float 2048 512 6177 Deadtime deadtime2 float 4 1 8225 Overload overload2 float 4 1 8229 GRS Temperature grstemp2 float 4 1 8233 Earth receive time ert2 float 4 1 8237 Spacecraft height hgt2 float 4 1 8241 Spacecraft latitude lat2 float 4 1 8245 Spacecraft longitude lon2 float 4 1 8249 Accepted spectra accnum[512] float 2048 512 filesize-4124 Rejected spectra rejnum[512] float 2048 512 filesize-2076 Deadtime deadtimenum float 4 1 filesize-28 Overload overloadnum float 4 1 filesize-24 GRS Temperature grstempnum float 4 1 filesize-20 Earth receive time ertnum float 4 1 filesize-16 Spacecraft height hgtnum float 4 1 filesize-12 Spacecraft latitude latnum float 4 1 filesize-8 Spacecraft longitude lonnum float 4 1 filesize-4 *The notation for variable names is the following: 1) A subscript after the variable name indicates a particular element of an array. For example, the first element of the array lat is designated lat1. 2) An entire array is designated by a square brackets. For example, the first 512-element accepted array is designated acc1[512]. This same variable naming convention holds true for the other tables in this document. 3. LP-NS Data Products 3.1 Naming Convention for LP-NS Files The neutron data has eleven different types of neutron data products. These include thermal and epithermal neutrons from high and low altitude. Each of the thermal and epithermal neutron datasets has data taken over 8 and 32 second sample periods. There are two fast neutron datasets of high and low altitude. Finally, there is one dataset of low altitude moderated neutrons. The file naming convention for the binary files is the following: type_neutron_xxxysec.bin, where * type gives the type of neutron and can be either thermal, epithermal, fast or moderated. * xxx tells whether the dataset is high or low altitude. * y tells whether the dataset is 8 or 32 second sample period. There are eight additional binary files that contain position information and are named position_xxxysec.bin, where the xxx and y carry the same information as above. Auxiliary files, named type_neutron_xxxysec.txt, contain supplementary information about the files such as the date and time the data were processed and written into binary files. 3.2. Contents of LP-NS Files The reduction of LP-NS time-series data are described in Maurice et al., [2003] and does not need to be repeated here. Table 2 lists the contents of the files containing 32 second period data, except for the 32-second moderated neutrons (see Table 4). The first four bytes in each file are a value of type long that give the total number of samples, named num, in each file. Following the first four bytes are the data values. For the type_neutron_xxx32sec.bin files, these data are a single array containing num elements. For the position_xxx32sec.bin files, there are the four products of latitude, longitude, spacecraft height, and Earth receive time. Table 3 lists the contents of the files containing 8-second period data. The first four bytes in each file are a value of type long that give the total number of samples, named num, in each file. Following the first four bytes are the data values. For the type_neutron_xxx8sec.bin files, these data are a single array containing num elements. For the position_xxx8sec.bin files, there are the two products of latitude and longitude. Finally, Table 4 lists the contents of the file moderated_neutron_low32sec.bin. This file contains both the low altitude moderated neutron data and position information for these data. Table 2: Contents of 32 second neutron and position files. File name Product name variable Data Total Total Start name type bytes items byte thermal_neutron_ number of num long 4 1 1 xxx32sec.bin samples thermal therms float 4*num 1 5 neutrons [num] epithermal_neutron_ number of xxx32sec.bin samples num long 4 1 1 epithermal epis float 4*num 1 5 neutrons [num] fast_neutron_ xxx32sec.bin number of num long 4 1 1 samples fast neutrons fast float 4*num 1 5 [num] position_ number of num long 4 1 1 xxx32sec.bin samples latitude lat[num] float 4*num 1 5 longitude lon[num] float 4*num 1 5+4*num height hgt[num] float 4*num 1 5+8*num earth receive ert[num] float 4*num 1 5+12*num time Table 3: Contents of 8 second neutron and position files. File name Product name variable Data Total Total Start name type bytes items byte thermal_neutron_ number of num long 4 1 1 xxx8sec.bin samples thermal therms float 4*num 1 5 neutrons [num] epithermal_neutron_ number of num long 4 1 1 xxx8sec.bin samples epithermal epis float 4*num 1 5 neutrons [num] position_ number of num long 4 1 1 xxx8sec.bin samples latitude lat[num] float 4*num 1 5 longitude lon[num] float 4*num 1 5+4*num Table 4: Contents of 32 second moderated neutron file. File name Product name variable Data Total Total Start name type bytes items byte moderated_neutron_ number of num long 4 1 1 low32sec.bin samples moderated moderated float 4*num 1 5 neutrons [num] latitude lat[num] float 4*num 1 5+4*num longitude lon[num] float 4*num 1 5+8*num height hgt[num] float 4*num 1 5+12*num earth receive ert[num] float 4*num 1 5+16*num time 4. References Feldman, W. C., K. Ahola, B. L. Barraclough, R. D. Belian, R. K. Black, R. C. Elphic, D. T. Everett, K. R. Fuller, J. Kroesche, D. J. Lawrence, S. L. Lawson, J. L. Longmire, S. Maurice, M. C. Miller, T. H. Prettyman, S. A. Storms, G. W. Thornton, The Gamma-Ray, Neutron, and Alpha-Particle Spectrometers for the Lunar Prospector Mission, J. Geophys. Res., submitted, 2003. Lawrence, D. J., Maurice, S., and W. C. Feldman, Gamma-ray Measurements from Lunar Prospector: Time-Series Data Reduction for the Gamma-Ray Spectrometer, J. Geophys. Res., submitted, 2003. Maurice, S. D. J. Lawrence, W. C. Feldman, R. C. Elphic, and O. Gasnault, Reduction of Neutron Data from Lunar Prospector, J. Geophys. Res., submitted, 2003.