Digital Data from the Great Sand Dunes Airborne Gravity Gradient Survey, South-Central Colorado By Drenth, B.J.1, Abraham, J.D.1, Grauch, V.J.S.1, Labson, V.F.1, and G. Hodges2 1U.S. Geological Survey 2Fugro Airborne Surveys Corp. USGS Open-File Report 2013-1011 This report contains digital data and supporting explanatory files describing data types, data formats, and survey procedures for a high-resolution airborne gravity gradient (AGG) survey at Great Sand Dunes National Park, Alamosa and Saguache Counties, south-central Colorado. In the San Luis Valley, the Great Sand Dunes survey covers a large part of Great Sand Dunes National Park and Preserve. The digital files include grids and flight-line data. The data files and information about their formats and use are organized into folders (directories) as follows. Files pertaining to the gridded data are contained in the "grids" folder; files pertaining to the flight-line data are contained in the "linedata" folder. In each folder, ASCII files with the extension "txt" describe the format and contents of the data files. Read the "txt" files before using the data files. To begin, refer to the report and Appendix1 files, as they discuss data processing and list and describe the files available in the folders. CONTACT INFORMATION Benjamin Drenth U.S. Geological Survey Box 25046 Mail Stop 964 Denver Federal Center Denver, CO 80225-0046 Telephone: (303) 236-1827 E-mail: bdrenth@usgs.gov DISCLAIMERS: This database, identified as OFR 2013-1011, has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also contains copyrighted materials as noted in the text. Permission to reproduce copyrighted items for other than personal use must be secured from the copyright owner. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein. LIST OF FILES 00Readme.txt 2013-1011_OFR.pdf Datafiles: Linedata 11088_AGGFin.zip 11088_2_AGGFin.XYZ 11088_1_AGGFin.gdb 11088_1_AGGFin.XYZ 11088_2_AGGFin.gdb Grids Conformed_gravity_2p67.gxf Area2_Gdd_fourier_2p67.gxf Area2_Gdd_fourier_0p00.gxf Area1_Gdd_fourier_2p67.gxf Area1_Gdd_fourier_0p00.gxf 0 GXINFO.TXT Metadata GSD_AGG-meta.txt HOW TO OBTAIN THE DIGITAL FILES The digital files constituting this report can be obtained via the Internet from the U.S. Geological Survey publications website. Go to the web page at http://pubs.usgs.gov/of/2013/1011/ and follow the directions to download the files. The main product is a Portable Document Format (.pdf) pamphlet, and maps, which requires Adobe Acrobat for viewing, and from which paper copies may be printed. Acrobat software runs on a variety of systems, and is available for download free of charge from Adobe at http://www.adobe.com. ArcReader may be downloaded free of charge from http://www.esri.com/software/arcgis/arcreader/download.htm for viewing additional files included in this report.