This is the README file for D2GMT D2GMT contains the Dynamics Explorer-2 (D2) Geiger-Mueller Tube (GMT) data that was included with the LAPI VAX binary data file. The D2GMT CDF files were generated by converting the VAX binary format stored at the Space Physics Data Facility (SPDF). The VAX binary format was converted from the original Sigma-9 machine that was used to collect and process Dynamics Explorer telemetry. As part of the LAPI experiment, there were two Geiger-Mueller Tubes for measuring high energy particles, one mounted at 0 degrees (sensor 0) and the second mounted at 90 degrees (sensor 1). The 0 deg GMT measures precipitating particles, whereas, the 90 deg GMT measures trapped particles above the LAPI energy range. The GMTs provide an integral measurement. Units available are: Description Units Comment Telemetry Dimensionless This is a compressed table index. counts/acc c/acc Uncompressed counts in accumulation interval. count rate c/s Counts normalized by accumulation period. Number Flux cnts/(cm**2-sr-s) integral measurement. GMT measurements are accumulated every second and are synchronized with the 1 second LAPI spectral measurement cycle. When the LAPI spectral measurement cycle is a multiple of 1 sec, the GMT measurement repeats to encompass 1 second measurements within the LAPI spectral measurement cycle. All variables are stored as 4 byte real numbers where -3.4e+38 is used to indicate a fill value. A status byte is included in this CDF and indicates the Status of processing achieved at Goddard Space Flight Center (GSFC). Status Meaning Number of Bits 0 SPDF Status Flag - All 8 Each bit which makes up the status byte was extracted so that each bit could be individually examined. These were labeled starting at bit 0 as follows: Status Meaning Number of Bits 1 SPDF StatusFlag - Bit 7 1 2 SPDF StatusFlag - Bit 6 1 3 SPDF StatusFlag - Bit 5 1 4 SPDF StatusFlag - Bit 4 1 6 SPDF StatusFlag - Bit 3 1 7 SPDF StatusFlag - Bit 2 1 8 SPDF StatusFlag - Bit 1 1 The SPDF Status byte defines the processing undergone when converting the original DE telemetry from its Sigma-9 format to its VAX binary format. The SPDF Status byte was meant to describe the values that were encountered when reading the Sigma-9 magnetic tape. Bits 3, 6, and 7 are contained within Status 0. Bit 3 indicates the SPDF Bad Sensor ID, bit 6 when the SPDF Previous Sensors Differs from the current sensors, and bit 7 when the SPDF detected a Time Gap in telemetry. The remainder of the bits were not defined in the SPDF documentation. These SPDF flags are specific to LAPI sensor data and telemetry. The geometric factors for the GMTs are the same, 1.93349e-3 cm**2 sr. The accumulation period is 1 sec. The conversion from the telemetry index into the number of counts in an accumulation period is as follows: TM ACTUAL TM ACTUAL TM ACTUAL TM ACTUAL INDEX COUNTS INDEX COUNTS INDEX COUNTS INDEX COUNTS 0 n/a 64 64.5 128 1054.5 192 16894.5 1 n/a 65 68.5 129 1118.5 193 17918.5 2 0.0 66 72.5 130 1182.5 194 18942.5 3 n/a 67 76.5 131 1246.5 195 19966.5 4 1.0 68 80.5 132 1310.5 196 20990.5 5 n/a 69 84.5 133 1374.5 197 22014.5 6 2.0 70 88.5 134 1438.5 198 23038.5 7 n/a 71 92.5 135 1502.5 199 24062.5 8 3.0 72 96.5 136 1566.5 200 25086.5 9 n/a 73 100.5 137 1630.5 201 26110.5 10 4.0 74 104.5 138 1694.5 202 27134.5 11 n/a 75 108.5 139 1758.5 203 28158.5 12 5.0 76 112.5 140 1822.5 204 29182.5 13 n/a 77 116.5 141 1886.5 205 30206.5 14 6.0 78 120.5 142 1950.5 206 31230.5 15 n/a 79 124.5 143 2014.5 207 32254.5 16 7.0 80 130.5 144 2110.5 208 33790.5 17 n/a 81 138.5 145 2238.5 209 35838.5 18 8.0 82 146.5 146 2366.5 210 37886.5 19 n/a 83 154.5 147 2494.5 211 39934.5 20 9.0 84 162.5 148 2622.5 212 41982.5 21 n/a 85 170.5 149 2750.5 213 44030.5 22 10.0 86 178.5 150 2878.5 214 46078.5 23 n/a 87 186.5 151 3006.5 215 48126.5 24 11.0 88 194.5 152 3134.5 216 50174.5 25 n/a 89 202.5 153 3262.5 217 52222.5 26 12.0 90 210.5 154 3390.5 218 54270.5 27 n/a 91 218.5 155 3518.5 219 56318.5 28 13.0 92 226.5 156 3646.5 220 58366.5 29 n/a 93 234.5 157 3774.5 221 60414.5 30 14.0 94 242.5 158 3902.5 222 62462.5 31 n/a 95 250.5 159 4030.5 223 64510.5 32 15.0 96 262.5 160 4222.5 224 67582.5 33 16.0 97 278.5 161 4478.5 225 71678.5 34 17.0 98 294.5 162 4734.5 226 75774.5 35 18.0 99 310.5 163 4990.5 227 79870.5 36 19.0 100 326.5 164 5246.5 228 83966.5 37 20.0 101 342.5 165 5502.5 229 88062.5 38 21.0 102 358.5 166 5758.5 230 92158.5 39 22.0 103 374.5 167 6014.5 231 96254.5 40 23.0 104 390.5 168 6270.5 232 100351.0 41 24.0 105 406.5 169 6526.5 233 104447.0 42 25.0 106 422.5 170 6782.5 234 108543.0 43 26.0 107 438.5 171 7038.5 235 112639.0 44 27.0 108 454.5 172 7294.5 236 116735.0 45 28.0 109 470.5 173 7550.5 237 120831.0 46 29.0 110 486.5 174 7806.5 238 124927.0 47 30.0 111 502.5 175 8062.5 239 129023.0 48 31.5 112 526.5 176 8446.5 240 135167.0 49 33.5 113 558.5 177 8958.5 241 143359.0 50 35.5 114 590.5 178 9470.5 242 151551.0 51 37.5 115 622.5 179 9982.5 243 159743.0 52 39.5 116 654.5 180 10494.5 244 167935.0 53 41.5 117 686.5 181 11006.5 245 176127.0 54 43.5 118 718.5 182 11518.5 246 184319.0 55 45.5 119 750.5 183 12030.5 247 192511.0 56 47.5 120 782.5 184 12542.5 248 200703.0 57 49.5 121 814.5 185 13054.5 249 208895.0 58 51.5 122 846.5 186 13566.5 250 217087.0 59 53.5 123 878.5 187 14078.5 251 225279.0 60 55.5 124 910.5 188 14590.5 252 233471.0 61 57.5 125 942.5 189 15102.5 253 241663.0 62 59.5 126 974.5 190 15614.5 254 249855.0 63 61.5 127 1006.5 191 16126.5 255 258047.0 From the telemetry index, the above look-up table gives the number of counts in an accumulation interval. The number of counts in an accumulation period is corrected by dividing by the detector efficiency. The corrected From the telemetry index, the above look-up table gives the number of counts in an accumulation interval. The number of counts in an accumulation interval is divided by the accumulation period to give the count rate. The count rate is divided by the geometric factor to give the number flux.