

<front cover>



U.S. Department of the Interior
U.S. Geological Survey


Aeromagnetic Surveying in Wisconsin 1998-99:
Digital Data Files


By Robert E. Bracken
and Suzanne W. Nicholson


Logistics Report
by High-Sense Geophysics Limited


U.S. Geological Survey
Open-File Report
99-527


1999



<back cover>



U.S. Department of the Interior
U.S. Geological Survey

Aeromagnetic Surveying in Wisconsin 1998-99:  Digital Data Files
By Robert E. Bracken and Suzanne W. Nicholson


 This CD-ROM contains aeromagnetic data obtained between
September 1998 and February 1999 over a large area in southern
Wisconsin. The survey was flown and the data were processed by
High-Sense Geophysics Limited, under contract with the U.S.
Geological Survey.  The total flight distance was about 46,000
line-miles (74,000 km) with traverse lines spaced at 1/2-mile
(805m) and oriented in a north-south direction.  The altitude was
draped to topography at 1000 feet (305m) above ground level.

The aeromagnetic data on this CD-ROM include:  (1) Flight-line
data with measurements taken at 1/10-second intervals given in a
compressed ASCII format; (2) Flight-line data winnowed to
1-second intervals given in a (non-compressed) ASCII format;  (3)
Grids of residual magnetic intensity using a Universal Transverse
Mercator projection given in several file formats; and (4) an
image of the aeromagnetic data given in four graphics formats
with three levels of resolution.

Files on this CD-ROM disc were generated on a PC under the
Microsoft Windows NT operating system, and are most easily
accessed by a PC using one of the common Windows operating
systems.  However, the folders and files are arranged such that
the information and data may be accessed from a larger variety of
computer systems.

The report and data may be accessed easily through the main
entry-point, a file called read_1st, found in the main folder of
this CD-ROM, Wisc1999\.  Several "read" files, found throughout
the report, are given in three optional formats:  ASCII Text
(TXT), Adobe Portable Document File (PDF), and Microsoft Word
Document (DOC). The PDF and DOC files contain links for rapidly
accessing images and information objects. Viewing the PDF files
requires Adobe Acrobat Reader software, which has been made
available on this CD-ROM.  The TXT files may be viewed using
practically any reader or editor.

Sufficient hard disk space is needed to accommodate the line and
gridded data files, which range in size from 9 Mb (smallest
winnowed line data) to 230 Mb (largest line-data after
uncompressing). The minimum added requirements of the Acrobat
reader for a Windows 95/98 installation is about 10 Mb.   This
CD-ROM disc was produced in accordance with the ISO 9660
standard.


_________________________________________________________________

U.S. Geological Survey Open-File Report 99-527

Although all data and software released on this CD-ROM have been
used by the USGS, no warranty, expressed or implied, is made by
the USGS as to the accuracy of the data and related materials and
(or) the functioning of the software.  Any use of trade, product,
or firm names is for descriptive purposes only and does not imply
endorsement by the U.S. Government.
