Survey number: 3177 (Pat Hill numbers)
Name: Chugach (gridded data)
Date flown: June/July 1979
Company: LKB
Flight specs: 1 mile spacing, N50W flightlines, 1000 ft above ground
Instrument: 

Datum: IGRF applied

Publication: USGS Open-file report 80-058

Data format: Ascii format, gridded data from contractor 
Row 1, Col 1 is in SW corner of area.

1. Row number (I5)
2. Column number (I5)
3. UTM Easting to the nearest meter (F10.0) 
4. UTM Northing to the nearest meter (F10.0)
   Note on UTM coordinates: Central meridian = -147 degrees
                            False easting = 500000 m

   Guess on meaning of two mag values:

5. Adjusted (IGRF removed, but 56,000 nT added back) magnetic intensity value,
   in nT (F10.2)
6. Gridded magnetic intensity value before IGRF removal, in nT (F10.2)

First three lines of file:

ANCHORAGE              ALASKA  LKB RESOURCESUNIVAC1108
   23  351   473700.  6759900.  56321.73  57385.32
   23  352   474000.  6759900.  56318.66  57381.46

Background: These data included in grid compilation for Interior Alaska
            (for published USGS Map GP-1014).  Work done by Rick Saltus,
            USGS, in cooperation with John Meyer, State of Alaska, 
            Division of Oil and Gas.  Data file reformatted by Saltus
            to correct column misalignment (probably a tape reading
            problem originally).