Airborne geophysical survey: Montana '79

Aeromagnetic data were collected along flight lines by instruments in an
aircraft that recorded magnetic-field values and locations. In the earlier
days of surveying, the only way to represent this data was to generate an
analog map with contour lines. This dataset is a representation of the
digitized contour lines either by following the lines or by choosing the
intersection of the contour and flight-line to create a value of the magnetic
field. The values presented are latitude, longitude, and map magnetic-field
values.

航空磁力数据（aeromagnetic data）由航空器搭载的仪器沿飞行航线采集，同步记录磁场强度与位置信息。在航空磁测的早期阶段，该类数据的唯一可视化表达方式为绘制带有等值线的模拟地图。本数据集是对原始模拟等值线的数字化重构产物，其数据通过两种方式生成：一是沿等值线轨迹逐点采集，二是选取等值线与飞行航线的交点以获取对应磁场强度数值。本次公开的数据集包含纬度、经度与测区磁场强度三类数据项。