SEAG data format SEAG1 -- Free-air gravity anomaly, date, GMT, and latitude and longitude in radians. South latitude and west longitude are negative. Data were processed using the 1930 International Gravity formula. If data are merged with depth information (output of program MRGDS), data will include depth values and a simple Bouguer anomaly. SEAG2 -- Free-air gravity anomaly, date, GMT, and latitude and longitude in radians. South latitude and west longitude are negative. Data were processed using the 1967 International Gravity formula. Basic format with gravity processing and computed free-air gravity anomaly as output from program ATS3. If depth data were collected during the cruise, it would have been merged with the SEAG data generated by program ATS3 by program MRGDS to compute a simple Bouguer anomaly. If program MRGDS was run, the SEAG format would also include the depth values. COLS FIELD NAME FORMAT ---- --------------------------- ------ 1 record type indicator = 2 I1 2-3 day I2 4-5 month I2 6-7 year I2 8-11 time of day (GMT as HHMM) I4 8-9 hour of day I2 10-11 minute of day I2 12-14 time zone I3 15-23 latitude (radians) F9.6 24-32 longitude (radians) F9.6 33-37 ship's velocity north (knots) I5 38-42 ship's velocity east (knots) I5 43-49 observed gravity (milligals) F7.1 50-54 free-air anomaly (milligals) F5.1 55-59 Bouguer anomaly (milligals) F5.1 60-64 current velocity north (knots) I5 65-69 current velocity east (knots) I5 70-74 corrected depth (meters) I5 75-77 depth correction (meters) I5 78-79 Matthews' table correction number I2 80-84 observed magnetic value (gammas) I5 85-89 Eotvos correction (milligals) F5.1 * OBSERVED GRAVITY: Total gravity field in milligals. The value is corrected for the Eotvos factor and may have been corrected for gravity-meter drift and for bias. Free-air and Bouguer anomalies have not been applied. * FREE-AIR ANOMALY: The calculated gravity anomaly, in milligals, at the data point. If data not available, the field equals 9999. * BOUGUER ANOMALY: If depth data are present, the Bouguer anomaly, in milligals, at the data point. If data not available, field equals 9999. * VELOCITY OF CURRENT NORTH & EAST: The difference between velocities calculated from the navigation fixes and those taken from the EM log. * MATTHEWS' TABLE: Matthews' table reference number 1-52. * OBSERVED MAGNETIC VALUE: If available, observed magnetic value for data point. * EOTVOS CORRECTION: The computed Eotvos correction that was applied to the raw gravity data. * Record Types: 1 = data processed using 1930 International gravity formula 2 = data processed using 1967 International gravity formula 9 = end of reel or data --------------------------------------------------------------------------- SEAG example output of program ATS3: 1 2 3 4 5 6 7 8 9 123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890 ------------------------------------------------------------------------------------------ 222 6761020 0 .550922-1.400567 616 769794496 13 9990 -78 55 0 0 00 0 91 222 6761025 0 .551052-1.400527 614 909794501 12 9990 -78 55 0 0 00 0 99 222 6761030 0 .551181-1.400483 608 1129794502 6 9990 -78 55 0 0 00 0 113 222 6761035 0 .551310-1.400436 611 1069794503 1 9990 -78 55 0 0 00 0 109 222 6761040 0 .551440-1.400392 616 989794504 -3 9990 -78 55 0 0 00 0 104 222 6761045 0 .551569-1.400349 621 879794508 -5 9990 -84 54 0 0 00 0 96 222 6761050 0 .551700-1.400311 621 779794511 -8 9990 -84 54 0 0 00 0 89 222 6761055 0 .551818-1.400245 525 2769794527 2 9990 -84 54 0 0 00 0 223 222 6761100 0 .551924-1.400144 515 3259794545 15 9990 -84 54 0 0 00 0 255 222 6761105 0 .552027-1.400037 511 3209794552 17 9990 -84 54 0 0 00 0 252 SEAG example output of program MRGDS: 1 2 3 4 5 6 7 8 9 123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890 ------------------------------------------------------------------------------------------ 222 6761020 0 .550922-1.400567 616 769794496 13 38 -78 55 36 1 90 0 91 222 6761025 0 .551052-1.400527 614 909794501 12 37 -78 55 36 1 90 0 99 222 6761030 0 .551181-1.400483 608 1129794502 6 31 -78 55 36 0 90 0 113 222 6761035 0 .551310-1.400436 611 1069794503 1 26 -78 55 36 0 90 0 109 222 6761040 0 .551440-1.400392 616 989794504 -3 22 -78 55 36 0 90 0 104 222 6761045 0 .551569-1.400349 621 879794508 -5 20 -84 54 36 0 90 0 96 222 6761050 0 .551700-1.400311 621 779794511 -8 17 -84 54 36 1 90 0 89 222 6761055 0 .551818-1.400245 525 2769794527 2 28 -84 54 37 1 90 0 223 222 6761100 0 .551924-1.400144 515 3259794545 15 41 -84 54 38 2 90 0 255 222 6761105 0 .552027-1.400037 511 3209794552 17 43 -84 54 37 2 90 0 252 ---------------------------------------------------------------------------