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Navigation Data and Maps

Trackline Maps

Trackline maps were created with ESRI ArcGIS 9.3 software, exported to Adobe Illustrator for further editing, and saved in JPEG format. These images can be accessed through the links provided below or from within the cruisenav folder. The navigation data used to create these maps have not been corrected for the approximately 6-m offset between the shotpoint and GPS antenna (fig. 1). For more information about the GIS project, refer to the Software page.

The trackline maps contain links to the interactive profiles, printable profiles, and line navigation maps. The line navigation maps, which have been corrected for the GPS offset, were created with CTI SonarWeb software and are stored in the linenav folder. Refer to the Profiles page for more information about the interactive and printable profiles.

Location Map

• Northern Islands
• Southern Islands
  

Processed Shotpoint Navigation

Shotpoint navigation files and 1,000-shot-interval location files were extracted from the trace headers of each line using Seismic Unix software. These files were then processed with PROJ.4 software (http://trac.osgeo.org/proj/) to generate UTM coordinates from latitude and longitude coordinates and reformatted for use with ESRI ArcGIS software. The processed navigation data have not been corrected for the offsets between the shotpoint and GPS antenna (fig. 1).

The processed shotpoint navigation and 1,000-shot-interval location files can be accessed through the links provided below or from within the nav folder. Each ASCII text file contains eight fields separated by commas and defined as follows:

Field 1: UTM X (Zone 16 North)
Field 2: UTM Y (Zone 16 North)
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 (UTC)

Processed Shotpoint Navigation (8.8-MB ASCII text file)

Processed 1,000-Shot-Interval Location Navigation (44.6-KB ASCII text file)

Raw Shotpoint Navigation

Shotpoint navigation files were extracted from the trace headers of each line using Seismic Unix software. Unprocessed navigation files are stored as ASCII text files in the rawnav folder by trackline number. These navigation data have not been corrected for the offset between the shotpoint and GPS antenna. Each file contains six fields separated by a space and defined as follows:

Field 1: Trackline Number
Field 2: Shotpoint Number
Field 3: Longitude (decimal degrees)
Field 4: Latitude (decimal degrees)
Field 5: Year
Field 6: Day of Year:Hour:Minute:Second (UTC)

NOTE: During data collection of line 07i47, the navigation system cable became disconnected from the acquisition system; consequently, no navigation data were collected between shot 584 and 9484 (an interval of approximately 30 minutes). This trackline is displayed as a dashed yellow line on the Northern Islands map (see link above), for additional information, please see the Metadata page.