EPIC SEG-Y Trace Header
EPIC SEG-Y utilizes big endian byte order and sets the various trace headers as outlined below.
EPIC SEG-Y Trace Header
| Byte Offset | Field Description |
| 0 - 3 | Line trace sequence number |
| 4 - 7 | Reel trace sequence number |
| 8 - 11 | Field record number |
| 12 - 15 | Field trace number |
| 16 - 19 | Energy source point number |
| 20 - 23 | Ensemble number |
| 24 - 27 | Trace number |
| 28 - 29 | Trace ID code |
| 30 - 31 | Number of vertically summed traces |
| 32 - 33 | Number of horizontally summed traces |
| 34 - 35 | Data use |
| 36 - 39 | Offset (distance) |
| 40 - 43 | Receiver group elevation |
| 44 - 47 | Source elevation |
| 48 - 51 | Source depth |
| 52 - 55 | Elevation at receiver group |
| 56 - 59 | Source elevation |
| 60 - 63 | Water depth at source |
| 64 - 67 | Water depth at group |
| 68 - 69 | Elevation and depth scalar |
| 70 - 71 | Coordinate scalar |
| 72 - 75 | X coordinate of source |
| 76 - 79 | Y coordinate of source |
| 80 - 83 | X coordinate of receiver group |
| 84 - 87 | Y coordinate of receiver group |
| 88 - 89 | Coordinate system |
| 90 - 91 | Weathering velocity |
| 92 - 93 | Sub-weathering velocity |
| 94 - 95 | Uphole time at source in ms |
| 96 - 97 | Uphole time at group in ms |
| 98 - 99 | Source static correction in ms |
| 100 - 101 | Group static correction in ms |
| 102 - 103 | Total static applied in ms |
| 104 - 105 | Lag time A, ms |
| 106 - 107 | Lag time B, ms |
| 108 - 109 | Delay recording time, ms |
| 110 - 111 | Mute start time, ms |
| 112 - 113 | Mute end time, ms |
| 114 - 115 | Number of samples |
| 116 - 117 | Sample interval, microseconds |
| 118 - 119 | Gain type |
| 120 - 121 | Gain constant |
| 122 - 123 | Early gain |
| 124 - 125 | Correlated? |
| 126 - 127 | Sweep frequency at start |
| 128 - 129 | Sweep frequency at end |
| 130 - 131 | Sweep length in ms |
| 132 - 133 | Sweep type |
| 134 - 135 | Sweep taper at start, ms |
| 136 - 137 | Sweep taper at end, ms |
| 138 - 139 | Taper type |
| 140 - 141 | Alias filter frequency, Hz |
| 142 - 143 | Alias filter slope, dB/octave |
| 144 - 145 | Notch filter frequency, Hz |
| 146 - 147 | Notch filter slope, dB/octave |
| 148 - 149 | Low-cut frequency, Hz |
| 150 - 151 | High-cut frequency, Hz |
| 152 - 153 | Low-cut slope, dB/octave |
| 154 - 155 | High-cut slope, dB/octave |
| 156 - 157 | Year |
| 158 - 159 | Day of Year |
| 160 - 161 | Hour |
| 162 - 163 | Minute |
| 164 - 165 | Seconds |
| 166 - 167 | Time bias code |
| 168 - 169 | Trace weighting for LSB |
| 170 - 171 | Geophone group number |
| 172 - 173 | Geophone group number (field) |
| 174 - 175 | Geophone group number, last trace (field) |
| 176 - 177 | Gap size |
| 178 - 179 | Over travel |
| 180 - 185* | station name code (5 chars + 1 for termination) |
| 186 - 193* | sensor serial code (7 chars + 1 for termination) |
| 194 - 197* | channel name code (3 chars +1 for termination) |
| 198 - 199* | extra bytes (2 chars) |
| 200 - 203* | sample interval in microsecs as a 32 bit integer |
| 204 - 205* | data format flag: 0=16 bit integer 1=32 bit integer |
| 206 - 207* | milliseconds of second for first sample |
| 208 - 209* | trigger time year |
| 210 - 211* | trigger time day of year |
| 212 - 213* | trigger time hour |
| 214 - 215* | trigger time minutes |
| 216 - 217* | trigger time seconds |
| 218 - 219* | trigger time milliseconds |
| 220 - 223* | scale factor (IEEE 32 bit float) (true amplitude = (data value)*(scale factor)/gain) |
| 224 - 225* | instrument serial number |
| 228 - 231* | number of samples as a 32 bit integer |
| 232 - 235* | max value in counts |
| 236 - 239* | min value in counts. |
| * extended SEG-Y header | |
| All unused fields in the trace header are set to 0x00 |
