Enhanced Grayscale TIFF Image of the 1-m Sidescan-Sonar Data From National Oceanic and Atmospheric Administration (NOAA) Survey H11251 Offshore of Rocky Point, New York (H11251_1MSSS_UTM18.TIF, UTM Zone 18, NAD83)

The sidescan-sonar data were acquired with a Klein T-5000 sidescan-sonar system hull mounted to an 8.5-m aluminum launch deployed from the NOAA ship Thomas Jefferson. The system was set to sweep 100 m to either side of the launch tracks. The sonar systems emitted two (port and starboard) 50 -wide beams tilted down 20 from horizontal, and transmitted at 455 kHz. The data were acquired in XTF (extended Triton data format), recorded digitally through an ISIS data acquisition system, and processed using CARIS SIPS (Sidescan Image Processing) software for quality control, and to produce a composite sidescan-sonar image at 1-m horizontal resolution. As part of this process, the sidescan-sonar data were demultiplexed and filtered to remove speckle noise and correct for slant-range distortions. Image 'shine through', to account for areas of overlap, and auto-contrast adjustment were applied. Contrast enhancement based on the dynamic range of the data was applied to the mosaic and it was then projected into UTM Zone 18 NAD83 to produce the image.

The image was imported into Adobe Photoshop CS2 in order to apply a linear stretch (i.e., increase the dynamic range of the data), to change image from RGB to 8-bit grayscale, to invert the grayscale to make strong reflections light tones and weak reflections returns darker tones, to correct tonal artifacts caused by improper cross-track normalization, and to assign a 'NO DATA' value (255).

The world (.tfw) file was renamed to match the new GeoTIFF name and GeoTIFFExamine was used to add the georeferencing information to the TIFF making the image a GeoTIFF.

ArcToolbox -Data Management Tools - Projections and Transformations - Define Projection Tool was used to define projection as UTM Zone 18 NAD83 in ArcGIS 9.2.

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 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.