A detailed aeromagnetic survey of Mono Basin and Long Valley, California was flown by EON Geosciences Inc. from October 25th to November 11th, 2012. The high-resolution helicopter survey was flown at a flightline spacing of 400 m, a flight-line azimuth of 65 degrees, a nominal flightline elevation above ground of 150 m, and consists of about 6,125 line-kilometers. Tie lines were spaced at a 4-km interval with a flightline azimuth of 155 degrees. A Scintrex CS-3 cesium magnetometer was used throughout the airborne survey and a GEM Systems GSM-19 magnetometer was used as a base station magnetometer located near the Mammoth Lake Yosemite airport. Data were processed by the contractor and include corrections for diurnal variations of the Earth's magnetic field, magnetic field of the helicopter, tie-line leveled, micro-leveled, and an International Geomagnetic Reference of the Earth for the time of the survey. Data presented include: survey report, ASCII database, a data dictionary, and a grid of residual magnetic intensity in nanoteslas (nT). Aeromagnetic maps derived from the survey were used and published by Peacock and others (2015).