Near-bottom AUV Sentry raw magnetic data (ASCII format) from 9°50'N, East Pacific Rise (2019, AT42-21)

Near-bottom magnetic data was collected at the East Pacific Rise, from 9°50'N, during a total of 20 AUV Sentry dives conducted from R/V Atlantis and R/V Roger Revelle during 2018 Atlantis cruise AT42-06 (three dives); 2019 Atlantis cruise AT42-21 (ten dives); and, 2021 Revelle cruise RR2102 (seven dives). Track lines were spaced 170 m apart, with Sentry about 70 m above bottom, collecting magnetic data using three Applied Physics Systems Model 1540 triaxial fluxgate magnetometers mounted on AUV Sentry. Sentry navigation was obtained using a 300 kHz Teledyne Doppler velocity log (DVL) and a Sonardyne AvTrak2 ultra-short baseline (USBL) acoustic positioning system, combined with an iXblue Phins inertial navigation system (INS), and a Paroscientific 8B7000-I Digiquartz depth sensor. The magnetic data are in ASCII text format, with one file each for top, port, and starboard magnetometers. Each ASCII file contains 11 columns, as follows: lon (degrees), lat (degrees), time (unix time, seconds), depth (m), altitude (m), roll (degrees), pitch (degrees), heading (degrees), X, Y, Z components of magnetic field strength (in oersted, i.e. x10^5 nT). Note that the magnetic data are X,Y,Z in sensor coordinates. The Sentry dive number and magnetometer mount point location is given in the file name. The three ASCII files for each dive correspond to one combined MATLAB file in an associated data set. Funding was provided by National Science Foundation awards OCE-1834797, OCE-1949485, OCE-1948936, and OCE-1949938.