USGS Geoscience Data Catalog
Additional USGS Geoscience data can be found by geographic location or by publication series.
U.S. Geological Survey, and National Geophysical Data Center, 2002, Aeromagnetic data for Wind River Basin, Wyoming:.This is part of the following larger work.
U.S. Geological Survey, and National Geophysical Data Center, 2001, Digital flight-line aeromagnetic data sets of the Conterminous United States, Hawaii, and Puerto Rico: U.S. Geological Survey Open-File Report 02-361, U.S. Geological Survey, Denver, CO.
This is a point data set.
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest .0001. Longitudes are given to the nearest .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 6,378,206.4.
The flattening of the ellipsoid used is 1/294.98.
Airborne survey specifications These items are constant for the entire survey Project number: 6001 Project name: Wind River Basin, Wyoming Survey compiled by: Texas Instruments, Inc. Survey flown by: Texas Instruments, Inc. Survey flown for: U.S. Atomic Energy Commission Approx. no. of line miles: 8378 Survey height: 400 ft Altitude method: Draped over terrain Flight-line spacing: 2 mi Flight-line direction: E-W Aircraft used: Douglas DC-3 Airport - arrival: Casper, WY Airport - departure: Casper, WY Magnetometer used: GeoMetrics G-803 proton precession Sensor tow distance: 100 feet
Each record contains the following 11 attributes: No abbrev.name contents 1 line_no flight line number 2 directn flight line direction, azimuth degrees from north (integer) 3 longitud longitude (decimal degrees) 4 latitude latitude (decimal degrees) 5 year year flown (integer) 6 jul_day Julian day flown (integer) 7 fiducial fiducial number (integer) 8 radar radar altimeter reading above ground (feet) 9 barom altitude above mean sea level (feet) 10 totmag corrected magnetic value (nT) 11 resmag residual magnetic value (nT)
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 542 |
| Units: | alphanumeric value |
| Range of values | |
|---|---|
| Minimum: | -1 |
| Maximum: | -1 |
| Units: | degrees |
| Range of values | |
|---|---|
| Minimum: | -109.8412 |
| Maximum: | -105.5056 |
| Units: | decimal degrees |
| Range of values | |
|---|---|
| Minimum: | 42.1644 |
| Maximum: | 43.5055 |
| Units: | decimal degrees |
| Range of values | |
|---|---|
| Minimum: | 1974 |
| Maximum: | 1974 |
| Range of values | |
|---|---|
| Minimum: | 126 |
| Maximum: | 172 |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 76730 |
| Range of values | |
|---|---|
| Minimum: | 216.0 |
| Maximum: | 4645.9 |
| Units: | feet |
| Range of values | |
|---|---|
| Minimum: | 5080.3 |
| Maximum: | 14054.9 |
| Units: | feet |
| Range of values | |
|---|---|
| Minimum: | 55968.00 |
| Maximum: | 71192.00 |
| Units: | nanoTeslas |
| Range of values | |
|---|---|
| Minimum: | -1032.22 |
| Maximum: | 14535.69 |
| Units: | nanoTeslas |
These USGS employees contributed to reformatting and archiving these data:
Viki Bankey, Carol Finn, Pat Hill, Holly Hindle, Bob Kucks, Vicki Rystrom, Sarah Shearer
Cooperating contributors from the National Geophysical Data Center are:
Ronald Buhmann, David Dater, Susan McLean, Stewart Racey
303-236-1343 (voice)
grav_mag@usgs.gov
Aeromagnetic surveys are used for geophysical prospecting. Some variations in magnetic measurements are caused by rocks that contain significant amounts of magnetic minerals (magnetite being the most common). These anomalies reflect variations in the amount and type of magnetic material and the shape and depth of the body of rock. Aeromagnetic anomaly maps are important tools in mapping surficial and buried igneous rocks. The features and patterns of aeromagnetic anomalies can also be used to delineate details of subsurface geology including the locations of buried faults and the thickness of surficial sedimentary rocks.
U.S. Geological Survey, 1999, Digitized Aeromagnetic Datasets of the Conterminous United States, Hawaii, and Puerto Rico: U.S. Geological Survey Open-File Report 99-557, U.S. Geological Survey, Denver CO.Online Links:
U.S. Atomic Energy Commission, 1975, Airborne geophysical survey, Wind River Basin area, Wyoming: Grand Junction Office Report GJO-1631-1, U.S. Atomic Energy Commission, Grand Junction, Colorado.
The data in this file have been processed using various formulas and
methods that are not usually documented but that represent
industry standard practices for airborne data reduction. For example,
position is listed as latitude and longitude, but these values
were derived from the raw navigation data depending on the system used.
(see notes under horizontal accuracy). Line numbers were added to
records, and unusable data at flight-line ends were discarded
(as aircraft slowed and turned around). Separate recordings were
correlated by time and assigned to the correct location.
The exact accuracies of these processing steps may not be known.
They are discussed in the sections on attribute or positional
accuracies.
Flight Path Recovery
Horizontal position of the survey aircraft used to collect
data were determined by reconciling down-looking photographs
(recorded on continuous-strip film) with topographic maps
and orthophotoquadrangle maps. Fiducial numbers and marks,
impressed on any paper strips that were recording data or
added to magnetic tape records, were included
as a function of time to further reconcile location with
instrumentation.
The aircraft vertical position was determined using the
navigational positioning equipment on the aircraft, which
were radar altimeter and barometric altimeter.
Radar altimeters are estimated to have an error
of 2-5% of the altitude (Richard Hansen, PRJ, Inc.,
written communication).
Barometric altimeters are quite accurate, but are
typically operated in an uncorrected mode. The
diurnal variation in air pressure over the course of
a flight can produce a 50-100 ft error in the
barometric altimeter reading. In addition, pressure microcells
create short-period air pressure changes equivalent
to about 10 ft under typical conditions (Richard
Hansen, PRJ, Inc., written communication)
The magnetometer was carried in a bird towed on a line
that was approximately 100 feet below the aircraft. The
bird as it is towed is slightly behind the aircraft and,
therefore, the vertical distance between the magnetometer
and the aircraft is slightly less than the length of the
line but remains constant for the survey.
This data set was collected at a draped survey having an
average terrain clearance of 400 feet. Because aircraft,
especially airplanes, cannot safely maintain a constant
terrain clearance, error in vertical position is introduced.
Loss of data due to poor transmission, channel dropout, obvious spiking,
missing channels, and other obvious errors were replaced with the
value -9999.9.
The contractor database did not have flight line direction (directn),
year (year), or fiducial (fiducial). A dummy value of -1 was used in
the directn channel to conform to the established template. The values
in the fiducial channel were generated with Oasis Montaj using the
latitude channel as a reference.
The data in this file were collected by a single contractor or group
who were responsible for collecting and processing the data.
The data from this survey were collected using the same instruments
(magnetometers, altimeters, navigational systems) throughout
the survey and were collected in a normal length of time with no long
delays between survey beginning and end.
Survey contracts specified the conditions and specifications under which
these data were collected. Standard industry practices of the time
were followed in data collection and processing.
Are there legal restrictions on access or use of the data?
- Access_Constraints: none
- Use_Constraints:
- none. Acknowledgement of the U.S. Geological Survey and the National Geophysical Data Center would be appreciated in products derived from these data.
303-202-4700 or 1-888-ASK-USGS (voice)
www.usgs.gov/pubprod
USGS Open-File Report OFR 02-0361
Although all data published on this CD-ROM have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
| Data format: |
Magnetic anomaly measurements
in format ASCII
Each line contains data in the following format, beginning with line 1(no header included): line_no I5 directn I4 longitud F11.4 latitude F9.4 year I5 jul_day I4 fiducial I7 radar F8.1 barom F8.1 totmag F9.2 resmag F9.2, 1X |
|---|---|
| Media you can order: |
CD-ROM
(format ISO 9660)
|
CD-ROM prices are subject to change. Please call or see <http://mapping.usgs.gov/esic/prices/>
Detailed instructions can be found at www.usgs.gov/pubprod
303-236-5486 (voice)
USGS Open-File Report OFR 02-0361
Although all data published on this CD-ROM have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
| Data format: |
Magnetic anomaly measurements
in format ASCII
Each line contains data in the following format, beginning with line 1 (no header included): line_no I5 directn I4 longitud F11.4 latitude F9.4 year I5 jul_day I4 fiducial I7 radar F8.1 barom F8.1 totmag F9.2 resmag F9.2, 1X |
|---|---|
| Network links: |
<ftp://ftpmusette.cr.usgs.gov/pub/NA_MAGNETICS/digital_data/WY/WY_6001.xyz.gz> |
303-236-1343 (voice)
grav_mag@usgs.gov
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://geo-nsdi.er.usgs.gov/metadata/open-file/02-361/WY/WY_6001.faq.html
Page Contact Information: Peter Schweitzer
Page Last Modified: Monday, 10-Nov-2008 12:19:35 EST
