obspy.io.segy.header.TRACE_HEADER_FORMAT

TRACE_HEADER_FORMAT = [[4, 'trace_sequence_number_within_line', False, 0], [4, 'trace_sequence_number_within_segy_file', False, 4], [4, 'original_field_record_number', False, 8], [4, 'trace_number_within_the_original_field_record', False, 12], [4, 'energy_source_point_number', False, 16], [4, 'ensemble_number', False, 20], [4, 'trace_number_within_the_ensemble', False, 24], [2, 'trace_identification_code', False, 28], [2, 'number_of_vertically_summed_traces_yielding_this_trace', False, 30], [2, 'number_of_horizontally_stacked_traces_yielding_this_trace', False, 32], [2, 'data_use', False, 34], [4, 'distance_from_center_of_the_source_point_to_the_center_of_the_receiver_group', False, 36], [4, 'receiver_group_elevation', False, 40], [4, 'surface_elevation_at_source', False, 44], [4, 'source_depth_below_surface', False, 48], [4, 'datum_elevation_at_receiver_group', False, 52], [4, 'datum_elevation_at_source', False, 56], [4, 'water_depth_at_source', False, 60], [4, 'water_depth_at_group', False, 64], [2, 'scalar_to_be_applied_to_all_elevations_and_depths', False, 68], [2, 'scalar_to_be_applied_to_all_coordinates', False, 70], [4, 'source_coordinate_x', False, 72], [4, 'source_coordinate_y', False, 76], [4, 'group_coordinate_x', False, 80], [4, 'group_coordinate_y', False, 84], [2, 'coordinate_units', False, 88], [2, 'weathering_velocity', False, 90], [2, 'subweathering_velocity', False, 92], [2, 'uphole_time_at_source_in_ms', False, 94], [2, 'uphole_time_at_group_in_ms', False, 96], [2, 'source_static_correction_in_ms', False, 98], [2, 'group_static_correction_in_ms', False, 100], [2, 'total_static_applied_in_ms', False, 102], [2, 'lag_time_A', False, 104], [2, 'lag_time_B', False, 106], [2, 'delay_recording_time', False, 108], [2, 'mute_time_start_time_in_ms', False, 110], [2, 'mute_time_end_time_in_ms', False, 112], [2, 'number_of_samples_in_this_trace', 'H', 114], [2, 'sample_interval_in_ms_for_this_trace', 'H', 116], [2, 'gain_type_of_field_instruments', False, 118], [2, 'instrument_gain_constant', False, 120], [2, 'instrument_early_or_initial_gain', False, 122], [2, 'correlated', False, 124], [2, 'sweep_frequency_at_start', False, 126], [2, 'sweep_frequency_at_end', False, 128], [2, 'sweep_length_in_ms', False, 130], [2, 'sweep_type', False, 132], [2, 'sweep_trace_taper_length_at_start_in_ms', False, 134], [2, 'sweep_trace_taper_length_at_end_in_ms', False, 136], [2, 'taper_type', False, 138], [2, 'alias_filter_frequency', False, 140], [2, 'alias_filter_slope', False, 142], [2, 'notch_filter_frequency', False, 144], [2, 'notch_filter_slope', False, 146], [2, 'low_cut_frequency', False, 148], [2, 'high_cut_frequency', False, 150], [2, 'low_cut_slope', False, 152], [2, 'high_cut_slope', False, 154], [2, 'year_data_recorded', False, 156], [2, 'day_of_year', False, 158], [2, 'hour_of_day', False, 160], [2, 'minute_of_hour', False, 162], [2, 'second_of_minute', False, 164], [2, 'time_basis_code', False, 166], [2, 'trace_weighting_factor', False, 168], [2, 'geophone_group_number_of_roll_switch_position_one', False, 170], [2, 'geophone_group_number_of_trace_number_one', False, 172], [2, 'geophone_group_number_of_last_trace', False, 174], [2, 'gap_size', False, 176], [2, 'over_travel_associated_with_taper', False, 178], [4, 'x_coordinate_of_ensemble_position_of_this_trace', False, 180], [4, 'y_coordinate_of_ensemble_position_of_this_trace', False, 184], [4, 'for_3d_poststack_data_this_field_is_for_in_line_number', False, 188], [4, 'for_3d_poststack_data_this_field_is_for_cross_line_number', False, 192], [4, 'shotpoint_number', False, 196], [2, 'scalar_to_be_applied_to_the_shotpoint_number', False, 200], [2, 'trace_value_measurement_unit', False, 202], [4, 'transduction_constant_mantissa', False, 204], [2, 'transduction_constant_exponent', False, 208], [2, 'transduction_units', False, 210], [2, 'device_trace_identifier', False, 212], [2, 'scalar_to_be_applied_to_times', False, 214], [2, 'source_type_orientation', False, 216], [4, 'source_energy_direction_mantissa', False, 218], [2, 'source_energy_direction_exponent', False, 222], [4, 'source_measurement_mantissa', False, 224], [2, 'source_measurement_exponent', False, 228], [2, 'source_measurement_unit', False, 230], [8, 'unassigned', False, 232]]

The format of the 240 byte long trace header.