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U.S. Geological Survey Data Series 496

Navigation Data and Maps


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Trackline Maps

Trackline maps were generated with ESRI ArcGIS 8.3 software, exported to Adobe Illustrator for further editing, and saved in JPEG format. These images are located in the maps folder. For details about the GIS project included on this disc, refer to the Software page.

Click on the links below to view the trackline maps.

FULL SURVEY AREA


Processed Shotpoint Navigation

Navigation files were extracted from the trace headers of each line using Triton Elics International, Inc. (TEI) software. These files were edited to remove spurious data points and fix incorrectly recorded dates. The navigation files were then processed with PROJ.4 software (http://www.trac.osgeo.org/proj/) to generate Zone 17 UTMs from latitude and longitude and reformatted for use with ESRI GIS software. The 500-shot-interval location files were extracted using Seismic Unix software and processed in the same manner as the navigation files. The navigation data have not been corrected to reflect the offset between the shotpoint and GPS antenna.

The navigation information was recorded in two locations in the original SEG-Y headers. The navigation in the defined fields is only accurate to 1 s of arc or approximately 31 m. The navigation stored in the undefined fields and used here to produce the trackline maps and these navigation files and is accurate to the degree of the GPS receiver or 3-5 m. The navigation files provided here were extracted from the undefined fields using Delph Seismic provided software.

The edited shotpoint navigation file and edited 500-shot-interval location file are accessible through the links provided below or from within the nav folder. These ASCII text files contain eight comma-delimited fields and are defined as follows:

Field 1: UTM-X (Zone 17)
Field 2: UTM-Y (Zone 17)
Field 3: Trackline Number
Field 4: Shotpoint Number
Field 5: Longitude (decimal degrees)
Field 6: Latitude (decimal degrees)
Field 7: Year
Field 8: Day of Year Hour Minute Second (GMT)

Processed Shotpoint Navigation (13.6-MB ASCII text file)

Processed 500-Shot-Interval Location Navigation (24-KB ASCII text file)

NOTE: Location navigation is not available for the last 1,161 shots of line sl26 due to an equipment malfunction.


Raw Shotpoint Navigation

Raw navigation data were extracted from the trace headers of each line using TEI software. Raw navigation files for each line are stored as ASCII text files in the rawnav folder. The navigation data have not been corrected to reflect the offset between the shotpoint and GPS antenna. These ASCII text files contain eight space-delimited fields and are defined as follows:

Field 1: Shotpoint Number
Field 2: Longitude (decimal degrees)
Field 3: Latitude (decimal degrees)
Field 4: Heading
Field 5: Speed
Field 6: Depth
Field 7: Date (Month/Day/Year)
Field 8: Time (Hour:Minute:Second in GMT)

NOTE: These data contain errors and have not been edited.

NOTE: ASCII text files may be viewed on a PC using Notepad or Wordpad.


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URL: http://pubs.usgs.gov/ds/496/html/nav.htm
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Page Last Modified: Monday, 28-Nov-2016 15:15:07 EST