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U.S. Geological Survey Data Series 724

Navigation Data and Maps


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The trackline maps listed below represent the vessel position during the survey, since the navigation data used to create these maps have not been corrected for the offset between the GPS antenna and the chirp's towfish (fig. 1).  The trackline maps were created with Environmental Systems Research Institute (ESRI) ArcGIS 10 software, exported to Adobe Illustrator for further editing, and saved in Joint Photographic Experts Group (JPEG) format. These images can be accessed through the links provided below or from within the maps folder. For more information about the GIS project, refer to the Software page.

Trackline Maps

10BIM04 Location Map
10BIM04 Area 1 Map


Processed Shotpoint Navigation

In addition to shotpoint navigation files, 1,000-shot-interval files were generated to help correlate shot locations on the map with evenly spaced 1,000-shot index markers along the top of the printable profile images. The shotpoint navigation files and 1,000-shot-interval location files were extracted from the trace headers of each line using Seismic Unix software via the readlljsfnew script (located in chirpll.tar, which can be found in the su folder). Shotpoint coordinates were then projected from latitude and longitude coordinates to Universal Transverse Mercator (UTM) northings and eastings (World Geodetic System 1984 (WGS84), Zone 16, m) using PROJ.4 software (http://trac.osgeo.org/proj/) and reformatted for use with ESRI GIS 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)
Field 2: UTM Y (Zone 16)
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)

10bim04.txt - Processed Shotpoint Navigation (55-MB ASCII text file)

s10bim04.txt - Processed 1,000-Shot-Interval Location Navigation (53-KB ASCII text file)


Raw Shotpoint Navigation

Shotpoint navigation files were extracted from the trace headers of each line using SU 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)


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