I . INTRODUCTION 



Using Vector Airborne Magnetometers (Schonstedt and Irons, 1955), 

 extensive aeromagnetic surveys of the magnitude and direction of the 

 earth's magnetic field have been carried out by the Oceanographic 

 Office since 1953. The primary purpose of this work has been to 

 chart the earth's main magnetic field, and as such the surveys have 

 been conducted at relatively high altitudes (6,000 - 20,000 feet), at 

 track spacings of 200 miles, and the reduction of data has been 

 limited to measurements at intervals of 15 - 20 miles along each track 

 line. 



Other requirements have necessitated fine grain, low level air- 

 borne surveys of specific ocean areas, from which detailed total 

 intensity information has been used to depict the magnetic field. The 

 processing and analysis of detailed vector data over oceanic features 

 have heretofore not been attempted. Using aeromagnetic survey data 

 collected over Plantagenet Bank, this report describes a method for 

 calculating the direction and magnitude of the anomalous field. In 

 addition, a computer technique is applied to estimate the shape, 

 location, and magnetic properties of the source body. 



