Navigation data

GPS navigation fixes were acquired at two-minute intervals throughout each cruise. The fixes were subsequently interpolated and merged with shot times to create a single navigation file for each cruise. These navigation files can be downloaded from Table 1. These files contain shot time (year, day-of-year, and GMT), reflection line number, shot number, and latitude and longitude for every shot. Navigation data are provided only for those portions of the cruises during which seismic data were acquired. Complete survey tracklines can be found on the USGS CMG InfoBank web site. Latitude and longitude values are not included in SEG-Y trace headers for either the reflection profiles or the sonobuoy records. When using the navigation files to determine shot locations for the sonobuoy records it is important to be aware that the line number in the navigation files refers to the reflection line number. The number of the reflection line along which a particular sonobuoy record was made can be found in both the SEG-Y EBCDIC header and the trace headers of the sonobuoy record. Shotpoint maps in PDF format are available for download from figure 10.