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Navigation

USGS Cruise MGNM 99023 Chirp Survey
Field Navigation Data & Shotpoint Maps

Click on each of the survey areas for a more detailed map and to view the seismic image files.

navigation map

Nearshore Area | Hudson Shelf Valley Area


Shotpoint Navigation Data

The navigation is stored in ASCII files using ten fields separated by commas.
  • Field 1: Longitude
  • Field 2: Latitude
  • Field 3: Line Number
  • Field 4: Shot Number
  • Field 5: UTM Zone 18 X
  • Field 6: UTM Zone 18 Y
  • Field 7: Year
  • Field 8: Hour
  • Field 9: Minute
  • Field 10: Second
  Shotpoint Maps:

Full Extent of Chirp Survey
Nearshore Area | Hudson Shelf Valley Area

Shotpoint Navigation Files (ASCII):

Full Extent of Chirp Survey Area

Raw Navigation Data

The raw navigation was collected using a differential GPS system (Ashtech). These files represent the raw data recorded on floppy disk aboard ship. The data are in NEMA format. WARNING: These data have not been checked for errors. Use with caution.

To aid viewing of the original raw navigation data, each data entry was reformatted (removing the NEMA codes) by filtering the raw data files through a UNIX awk script. Every navigation fix from the original data has been preserved, however.

The navigation is stored in ASCII files using six fields separated by tabs, with each file representing a separate julian day (i.e. jd208web.txt). Navigation fixes are at 10 second intervals. The start and end of each line is marked within each reformatted navigation file.
Download Files (click on the Julian Day):
Julian Day: 208 | 209 | 210 | 211 | 212
nearshore valley valley nearshore