Airborne geophysical survey: Susitna 2012

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What does this data set describe?

Title: Airborne geophysical survey: Susitna 2012
A high sensitivity fixed-wing magnetic airborne survey was carried out for U.S. Geological Survey (Client) from Skwentna Roadhouse, AK, USA, over the survey blocks known as: Sustina (A1), and Add-On. New-Sense Geophysics Ltd. (NSG) flew the survey under the terms of an agreement with Client dated September 7th, 2012. The survey was flown between October 11th and November 1st, 2012. A total of 10,827* line kilometers of field magnetic data were flown, collected, processed and plotted. Sustina (A1) Block: 7,700 km; Add-On Block: 3,127 km. The primary geophysical sensor was a high-sensitivity Cesium-3 magnetometer, mounted in a fixed tail stinger assembly. Airborne ancillary equipment included; iCAM (digital video recorder), iDAS data acquisition system, fluxgate magnetometer, radar altimeter, and global positioning system (GPS) receiver. The GPS system provided accurate real-time navigation and subsequent flight path recovery. Ground equipment included; high-sensitivity Cesium-3 magnetometer, iBASE data acquisition system, global positioning system (GPS) receiver, and PC-based field workstation. The GPS receiver was used for time synchronization with airborne data. The field computer was used to check the data quality and completeness on a daily basis.
  1. How might this data set be cited?
    U.S. Geological Survey, 2013, Airborne geophysical survey: Susitna 2012:.

    Online Links:

    This is part of the following larger work.

    Saltus, R.W., Anderson, E.D., and Limited, New-Sense Geophysics, 1999, Alaska digital aeromagnetic database description: U.S. Geological Survey Open-File Report 99-503.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -154.070028
    East_Bounding_Coordinate: -149.904028
    North_Bounding_Coordinate: 62.742167
    South_Bounding_Coordinate: 61.843417
  3. What does it look like? (JPEG)
    Reduced-size image depicting the data, 732 x 480 pixels, 99,100 bytes
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: Oct-2012
    Ending_Date: Nov-2012
    ground condition
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Entity point
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
  7. How does the data set describe geographic features?
    The majority of these surveys are available as digital flightline data (data for which digital records of original flightline data exist). We attempted to recover or construct the standard channels (fields) to be included in the final database for all digital flightline data. For some surveys, some of the standard channels (e.g., MAG_BASE ) were not available and were removed from the individual final database file. The standard channels are: Standard Database Channels For Digital Flightline Surveys
     Channel Name        Units               Description
     LINE                number              Line number
     LINE_DIRECTION      deg.                Line direction
     FLIGHT              number              Flight number
     DATE                Julian date         Date flown (YYYYDDD)
     FIDUCIAL            number              Fiducial count (flight specific)
     TIME               Operating system time
     SYSTEM_CLOCK        milsec              KANA8 (A/D converter) counter
     NAD27_X meters      NAD27               Easting, Z5N, Alaska mainland
     NAD27_Y meters      NAD27               Northing, Z5N, Alaska mainland
     WGS84_X meters      WGS84               Easting, Z5N, World
     WGS84_Y meters      WGS84               Northing, Z5N, World
     LATITUDE_NAD27      degrees             GPS latitude, NAD27, Alaska mainland
     LONGITUDE_NAD27     degrees             GPS longitude, NAD27, Alaska mainland
     GPS_HEIGHT_WGS84    meters              GPS height (orthometric) above MSL, WGS 84, World
     UTC_DAYSEC          decimal seconds     UTC daily second counter (0-86399)
     FLUX_X              volts               Fluxgate x-axis
     FLUX_Y              volts               Fluxgate y-axis
     FLUX_Z              volts               Fluxgate z-axis
     RAD_ALT_m           meters              Radar altimeter, height above ground
     MAG_RAW             nT                  Raw magnetometer data
     MAG_FILT            nT                  Filtered raw magnetometer data
     MAG_COMP            nT                  Compensated magnetometer data
     DIURNAL             nT                  Base station (diurnal) magnetometer data
     MAG_DIURNAL_CORR    nT                  Diurnal corrected magnetometer data
     MAG_HEADING_CORR    nT                  Heading corrected magnetometer data
     MAG_LAG_CORR        nT                  Lag corrected magnetometer data
     MAG_SMPL_LVL        nT                  Conventionally (simple) leveled magnetometer data
     IGRF                nT                  Calculated IGRF, 2010 model
     TMI_FINAL           nT                  Final TMI (IGRF corrected MAG_SMPL_LVL  data)
     VDV nT/m            1st                 Order Vertical Derivative
     TMI_sync            nT                  Synced final TMI to previously flown survey
    New-Sense Geophysics Limited Report (FINAL LOGISTICS REPORT-USGS- Sustina Airborne Survey 2012.pdf)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?

Why was the data set created?

The technical objective of the survey was to provide high-resolution total field magnetic maps suitable for anomaly delineation, detailed structural evaluation, and identification of lithologic trends. Fully corrected magnetic maps were prepared by New-Sense Geophysics Limited, in their Toronto office, after the completion of survey activities.

How was the data set created?

  1. From what previous works were the data drawn?
    paper (source 1 of 1)
    Connard, G.G., Saltus, R.W., Hill, P.L., Carlson, L., Milicevic, B., 1999, Alaska digital aeromagnetic database description: Open-File Report 99-503.

    Online Links:

    Type_of_Source_Media: paper
    Digital information were drawn from (or are presented in) this report
  2. How were the data generated, processed, and modified?
    Date: Oct-2012 to 201211 (process 1 of 4)
    Aeromagnetic survey flown by New-Sense Geophysics Limited in the time period 10/11/2012-11/01/2012 direction NW-SE at altitude 100 feet above ground (AG) with spacing between 0.5 and 1 miles for a total of 6728 line miles
    Date: 2012 (process 2 of 4)
    New-Sense Geophysics Limited was contracted by the U.S. Geological Survey (USGS) to carry out an airborne magnetic survey. These data were collected, processed, and plotted using industry standard techniques. The accompanying contractor's report (FINAL LOGISTICS REPORT-USGS- Sustina Airborne Survey 2012.pdf) provides detailed data processing documentation. Person who carried out this activity:
    U.S. Geological Survey, Mineral Resources Program
    Attn: Richard W. Saltus
    Mail Stop 964 Building 20 Denver Federal Center, West 6th Avenue and Kipling Streets
    Lakewood, Colorado

    303-236-1375 (voice)
    303-236-1425 (FAX)
    Date: Nov-2012 (process 3 of 4)
    USGS is providing contractor delivered digital data in ASCII format.
    Date: 10-Nov-2020 (process 4 of 4)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Recent aeromagnetic surveys such as this one have generally been carried out on contract by private-sector companies that specialize in these surveys. In some cases we will retain a report from the contractor detailing methods and survey parameters, which could be consulted in order to understand the likely accuracy of the measurements.
  2. How accurate are the geographic locations?
    Detailed positional information is determined by the contractor using navigational controls to specifications given in the contractor reports. Generally these are more precise and accurate for newer surveys than for older ones.
  3. How accurate are the heights or depths?
    The aircraft vertical position was determined using the navigational positioning equipment on the aircraft, which were radar altimeter and barometric altimeter.
  4. Where are the gaps in the data? What is missing?
    Observations were made along flight lines, so these data may not extend into all parts of the geographic bounding extents.
  5. How consistent are the relationships among the observations, including topology?
    In general each original survey was collected by a single contractor, who would be responsible for processing the field observations, and reflect industry standard practices and controls. Variation among surveys is possible, especially if they were carried out during very different time periods.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints: none
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey, Mineral Resources Program
    Attn: Peter N. Schweitzer
    Mail Stop 954 USGS National Center, 12201 Sunrise Valley Drive
    Reston, Virginia

    703-648-6533 (voice)
    703-648-6252 (FAX)
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Reference herein to any specific commercial product, process, or service by trade name,trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 10-Nov-2020
Metadata author:
U.S. Geological Survey, Mineral Resources Program
Attn: Peter N. Schweitzer
Mail Stop 954 USGS National Center, 12201 Sunrise Valley Drive
Reston, Virginia

703-648-6533 (voice)
703-648-6252 (FAX)
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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