Navigation
NAVIGATION FIELD DATA
Description
The directory rawnav located in directory nav contains the raw navigation
that was collected during the sidescan-sonar component of the field program using
a USGS differential GPS system (Ashtech). These files represent the data that
was originally recorded on floppy disk aboard ship. The data are in NEMA format,
but only contain the $GPGGA string. 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.(See SCRIPTS
sub-directory within the NAV directory). Every navigation fix from the original
data has been preserved.
The navigation is stored in ASCII files using six fields separated by tabs, with
each file representing a separate Julian Day (i.e. jd124web.txt). Navigation fixes
are at ~10 second intervals. These files are located in the NAV sub-directory.
- Field 1: Date and Time (julian day:hour (UTC):minute:second)
- Field 2: Latitude (i.e. 32d59.375 = 32 Degrees 59.375' North)
- Field 3: Longitude (i.e. -79d96.875 = 79 Degrees 96.875' West)
- Field 4: Speed (in knots, computed from the navigation)
- Field 5: Heading (in degrees, computed from the navigation, i.e.
course made good)
- Field 6: Water Depth (derived from an Odem 200 kHz subbottom profiler).
Depths are in meters, but have not been corrected for the depth of the transducer,
roughly 2 m below the sea surface, nor for the tide (for tidal information
and 6 minute tidal data, see NOAA's tide
server).
REFORMATTED NAVIGATION DATA
These links contain navigation in ASCII text format.
No data were collected on Julian Days 132, 133, 136--weather days.
3 May, 1996 (JD 124)
4 May, 1996 (JD 125)
5 May, 1996 (JD 126)
6 May, 1996 (JD 127)
7 May, 1996 (JD 128)
8 May, 1996 (JD 129)
9 May, 1996 (JD 130)
10 May, 1996 (JD 131)
13 May, 1996 (JD 134)
14 May, 1996 (JD 135)
16 May, 1996 (JD 137)
17 May, 1996 (JD 138)
18 May, 1996 (JD 139)
19 May, 1996 (JD 140)
20 May, 1996 (JD 141)
21 May, 1996 (JD 142)
22 May, 1996 (JD 143)
23 May, 1996 (JD 144)
24 May, 1996 (JD 145)
25 May, 1996 (JD 146)
26 May, 1996 (JD 147)
27 May, 1996 (JD 148)
28 May, 1996 (JD 149)
To Sidescan-Sonar Field data
Return to the data page
Return to USGS Cruise SEAX 96004 home page