Point Shapefile of All the Unique Seismic Shot Point Navigation Collected in the Potomac River/Chesapeake Bay from Sept. 6, 2006 to Sept. 8, 2006 on USGS Cruise 06018 (ALLSHOTS_GEOG.SHP)

The KEL SounderSuite acquisition system records two files with every seismic profile. The file containing the seismic data has the extension KEB. The files with the KEA extension are the ASCII navigation files. The prefix filenames are of the format LLLL_YYYY_JJJ_HHMM_FFF where LLLL refers to the line number, YYYY refers to the year of acquisition, JJJ refers to the Julian day of acquisition, HHMM refers to the hour and minute of the start of acquisition, and FFF refers to the file number associated with the line. Because the KEL software was set to increment the file number at 20,000 shots, it's possible to have multiple files for a single line of acquisition. An example filename is: 0024_2006_251_1733_002. This is line 24, collected in the year 2006 on Julian day 251 with a start time of 17:33. This is part 2 of line 24. KEB seismic files were converted to standard SEG-Y files using KEL's PostSurvey version 1.56 software. During the first two days of data acquisition (Julian day 249 and 250 - Sept. 6 and Sept 7), the seismic acquisition software failed to record the navigation data from the DGPS NEMA string in the KEB and KEA files. However, after receiving a patched version of the SounderSuite software, navigation was recorded in the KEB and KEA seismic files. The KEB file is the KEL format seismic profile, while the KEA files is the KEL ASCII navigation file. On the first two days, the KEA files recorded shot number and times. A time server was used to synchronize the GPS time on the KEL with the HYPACK navigation system as the KEL SounderSuite records system time. The prefix filenames are of the format LLLL_YYYY_JJJ_HHMM_FFF where LLLL refers to the line number, YYYY refers to the year of acquisition, JJJ refers to the Julian day of acquisition, HHMM refers to the hour and minute of the start of acquisition, and FFF refers to the file number associated with the line. Because the KEL software was set to increment the file number at 20,000 shots, it's possible to have multiple files for a single line of acquisition. An example filename is: 0024_2006_251_1733_002. This is line 24, collected in the year 2006 on Julian day 251 with a start time of 17:33. This is part 2 of line 24.

All KEB, KEA, and SEG-Y files were transferred to an external hard drive and transferred to a Mac OSX PowerBook for further processing. KEB files were converted to match-filtered standard SEG-Y using KEL's PostSurvey version 1.56 software.

The processed SEG-Y files were read and converted to SeismicUnix (SU) format trace data.

The shot number and time of day were extracted from the SU headers and saved in an ASCII file.

An AWK script was used to parse the one-second HYPACK navigation files to output time of day and UTM, zone 18 eastings and northings. A navigation file with Julian day, time, and UTM zone 18 coordinates was concatenated for each Julian day (coordinates were rounded to integers).

The ASCII navigation data were merged with the shot point and time files based on the common field of Julian day, hours, minutes, and seconds using the Unix command "join" on a Mac OS X computer. The output is a shot point navigation file with fixes every five shots (1 second) for the KEL Chirp data. Julian day 151 was processed the same even though position was available in the trace headers. A command line example of the join command is:

 join 0001_2006_249_1340_001.txt jd249_utm.txt >  0001_2006_249_1340_001.spt

An AWK script was run within a shell script on a Mac OS X to take the complete seismic navigation and reformat it with Cruise ID, linename, shot, easting and northing. The shell script formatjday:

#! /bin/csh
 awk '{FS=" "} {OFS=" "} {printf "%5s %25s %5.0f %6s %7s\n", \
cruise,line,$2,$3,$4,$1} ' cruise=06018 line=$1 $1.spt >> $2.spnav

This shell script could be called with the following command line example:

formatjday 0001_2006_249_1340_001 249

Each file from a single Julian day was combined into a single text file using the Unix "cat" command.

The combined file was renamed with the extension TXT and a header line was added to the file. This file was then added to ArcMap 9.0 as an event theme using Tools - Add XY data and defining the projection as UTM, zone 18, NAD83. The x field is the easting field, and the y field is the northing field. The event theme was then exported as a shapefile by right-mouse clicking on the theme - Data - Export.

The first recorded line for line 5 needed to be split into two parts. The file naming in terms of files as the ship travels was originally - part 2, part 1, part 4. In order to better use this shapefile for future work which will sort on filename, shots were renamed from "part 1" to fit in with the direction of boat travel so that now there is part 2, part 3, part 4. (the original part 1 is now part 3).

The shot point shapefile was reprojected to Geographic, NAD83 using ArcMap 9.2, ArcToolbox - Data management Tools - Projections and Transformations - Feature - Project. Because the input file and output file have the same datum, no datum transformation was required.

Edits to the metadata were made to fix any errors that MP v 2.9.32 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). The cross-reference link to the SEG Y publication was fixed. The source information was incomplete and had to be modified to meet the standard. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.

Added keywords section with USGS persistent identifier as theme keyword.