Shot point navigation at 500 shot intervals for EdgeTech SB-512i chirp seismic-reflection data collected by the U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center offshore of the Gulf Islands, MS, 2010 (ESRI point shapefile, 10cct02_SeismicShot_500.shp)

An executable C-shell script called on SIOSEIS (version 10.2.25) to: 1) read SEG-Y data processed by Arnell (Harrison) Forde of the St. Petersburg Coastal and Marine Science Center and create shot gathers containing two consecutive traces; 2) create a stacked trace from the two trace gathers while maintaining the navigation coordinates from the header of the first trace in each; and 3) write the stacked traces to new SEG-Y files. This stacking flow ensured that the resulting traces were spaced greater than 0.5 m apart along the trackline, which is a prerequisite for the traces to be loaded into GeoGraphix SeisVision (version R5000) for digital interpretation.

An executable C-shell script called on Seismic Unix (version 4.1) to read the stacked SEG-Y files, write a Seismic Unix file, and extract SEG-Y trace header information, including shot number, longitude, latitude, year, Julian day, and time of day (UTC) to ASCII text files for each survey line. The data were filtered using AWK (no version) to save records for the first and last shots, and shots at unique longitude/latitude positions in between (a .csv version of the unique shot point navigation is included in the WinZip file '10cct02_shots.zip' Geographic coordinates (WGS84) were converted to UTM zone 16 coordinates (WGS84) using Proj (version 4.6.0), and added to the text files in two new columns.

An additional AWK filter was applied to each file created in the previous step to extract trace header records containing the first and last shots, and shots evenly divisible by 500 for each survey line. A 500 shot interval was chosen because it corresponds to the annotation interval provided along the top of the seismic-reflection profile portable network graphic (PNG) images, which are included in the 'GIS_catalog\Seisimage\10cct02' directory.

Text files created in the previous step were concatenated into a comma-delimited text file, then imported into ArcMap (version 9.2) using 'Add XY data' and saved as points (Geographic, WGS84) in the ESRI shapefile format ('10cct02_SeismicShot_500.shp').

Edits to the metadata were made to fix any errors that MP v 2.9.36 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.). Fixed a link to the data in the Distribution_Information section. Attempted to modify http to https where appropriate. Added a landing page link as the first link in the identification section. Updated the link to the field activity. 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. Added a distribution format to account for the CSV file in the zip file. Fixed link to browse graphic. 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.