US Geological Survey, Procurement and Contracts Branch, 345 Middlefield Road, Mail Stop 285, Menlo Park CA 94025

D -- DIGITIZING SERVICES SOL RFP 00005. Contact Point, Warren Saul, Contract Specialist, 415/329-4168. The US Geological Survey requires the construction of digitally merged aeromagnetic data grids for the state of Alaska. These grids will provide basic geophysical information for a variety of studies including resource exploration and evaluation, hazard assessment, and other geologic and tectonic input. The goal of this digital compilation effort is the production of two grids, both with a 1 km grid spacing as follows: 1. A ``composite'' grid of the original data that has the correct International Geomagnetic Reference Field (IGRF) removed, erroneous data filtered out, and appropriate datum shifts applied to approximately match the adjacent survey levels, and 2. A ``merged'' grid with the original data being modified by mathematical upward or downward continuation and level-to-drape conversion (if necessary) applied to achieve a consistent merged specification of 1000 ft above ground. The following procedures shall be followed in order to maintain consistency of these data with other data sets already published: 1. The contractor shall construct a data grid from each individual survey. 2. The contractor shall contour and plot the individual data grids and eliminate data quality problems. 3. The contractor shall apply the Definitive Geomagnetic Reference Field (DGRF) for the date of the survey. 4. The contractor shall re-grid each survey grid, if necessary to the final grid cell size of 1km. 5. The contractor shall adjust the datum levels of the individual surveys to minimize the differences at the boundaries. 6. For each region, the contractor shall combine all individual surveys into a single grid, leaving small gaps (no-data areas) between surveys. 7. The Contractor shall upward or downward continue and convert from level to drape as necessary to convert each individual survey to a consistent specification of 1,000 ft above ground. 8. The contractor shall adjust the datum levels of the individual surveys to minimize the differences at the boundaries. 9. The contractor shall combine all the individual surveys into a single grid (with no data gaps) for each region. The grids shall be produced using the Albers conical equal-area projection. The raw digital flightline data for this compilation will be supplied to the contractor by the USGS. All interested parties and/or responsible sources shall respond, in writing, within 15 days of the publication of this notice indicating your ability to meet the requirements described herein. (164)

Loren Data Corp. http://www.ld.com (SYN# 0027 19960619\D-0003.SOL)