page_title: Aeromagnetic survey
section_title: Unexploded ordnance
hierarchical_section_title: Aeromagnetic survey / Unexploded ordnance
caption_attribution_description: English: The helicopter magnetometer detects magnetic anomalies on the ground or in shallow surfaces. The device flies six feet above ground at speeds of 30 to 40 mph. Photo courtesy U.S. Army Corps of Engineers contractor, Zapata.
context_page_description: An aeromagnetic survey is a common type of geophysical survey carried out using a magnetometer aboard or towed behind an aircraft. The principle is similar to a magnetic survey carried out with a hand-held magnetometer, but allows much larger areas of the Earth's surface to be covered quickly for regional reconnaissance. The aircraft typically flies in a grid-like pattern with height and line spacing determining the resolution of the data.
context_section_description: Aeromagnetic surveys are also used to perform reconnaissance mapping of unexploded ordnance.  The aircraft is typically a helicopter, as the sensors must be close to the ground (relative to mineral exploration) to be effective. Electromagnetic methods are also used for this purpose.
caption: This helicopter is equipped with a magnetometer array. It flies six feet above ground at speeds of 30 to 40 mph.
exif: {"Image ImageDescription": "OLYMPUS DIGITAL CAMERA", "Image Make": "OLYMPUS IMAGING CORP.", "Image Model": "u710,S710", "Image Orientation": "Horizontal (normal)", "Image XResolution": "314", "Image YResolution": "314", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Version 1.1", "Image DateTime": "2012:10:03 07:23:33", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "266", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 51, 48, 48, 0, 0, 37, 0, 1, 0, 20, 0, ... ]", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "7604", "Thumbnail JPEGInterchangeFormatLength": "8004", "EXIF ExposureTime": "1/200", "EXIF FNumber": "11", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "64", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2012:10:03 07:23:33", "EXIF DateTimeDigitized": "2012:10:03 07:23:33", "EXIF ComponentsConfiguration": "YCbCr", "EXIF ExposureBiasValue": "-3/10", "EXIF MaxApertureValue": "353/100", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Daylight fluorescent (D 5700 - 7100K)", "EXIF Flash": "Flash did not fire, auto mode", "EXIF FocalLength": "262/25", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3072", "EXIF ExifImageLength": "2304", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "722", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Manual Exposure", "EXIF WhiteBalance": "Manual", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "None", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}