COMM GENERAL COMM COMM Project 2273 COMM Survey area Heemskirk, NW Tasmania COMM Located data type 0.1 Second Final Data COMM COMM Surveyed by GPX AIRBORNE PTY LTD. COMM Job number 2273 COMM Processed by GPX AIRBORNE PTY LTD. COMM Creation date March 2007 COMM COMM SURVEY SPECIFICATIONS COMM COMM Survey flown February 2007 COMM Traverse line spacing 50 metres COMM Traverse line direction 090-270 degrees COMM Tie line spacing 500 metres COMM Tie line direction 000-180 degrees COMM COMM Survey height 80 metres COMM COMM LOCATED DATA FORMAT COMM COMM Variable Units Undefined From To Format COMM COMM Line number 9999999 1 8 I8 COMM Easting (GDA94, MGA55) metres 9999999.99 9 19 F11.2 COMM Northing (GDA94, MGA55) metres 9999999.99 20 30 F11.2 COMM Fiducial 99999.99 31 39 F9.2 COMM Flight number 999 40 43 I4 COMM Direction (1=E, 2=N, 3=W, 4=S) 9 44 45 I2 COMM Date (YYYYMMDD) 99999999 46 54 I9 COMM Time (GPS) seconds 99999.99 55 63 F9.2 COMM Longitude (WGS84) degrees 999.999999 64 74 F11.6 COMM Latitude (WGS84) degrees 999.999999 75 85 F11.6 COMM Radar altimeter metres 9999.9 86 92 F7.1 COMM GPS altitude metres 9999.9 93 99 F7.1 COMM Raw magnetics nT 99999.999 100 109 F10.3 COMM Post compensated magnetics nT 99999.999 110 119 F10.3 COMM Diurnal nT 99999.999 120 129 F10.3 COMM Final magnetics nT 99999.999 130 139 F10.3 COMM Pressure millibars 9999.9 140 146 F7.1 COMM Temperature degrees C 99.9 147 151 F5.1 COMM Raw total count cps 999999 152 158 F7.0 COMM Raw potassium cps 9999 159 163 F5.0 COMM Raw uranium cps 9999 164 168 F5.0 COMM Raw thorium cps 9999 169 173 F5.0 COMM Raw cosmic cps 99999.9 174 178 F5.0 COMM Final total count cps 99999.99 179 187 F9.2 COMM Final potassium cps 99999.99 188 196 F9.2 COMM Final uranium cps 99999.99 197 205 F9.2 COMM Final thorium cps 99999.99 206 214 F9.2 COMM Final DTM metres 99999.9 215 222 F8.1 COMM COMM DATA PROCESSING COMM COMM COORDINATE DATA COMM All lines are scissored to the following rules: COMM 1) A 'smooth' edge outside the area boundary. COMM 2) Maximum line overlap of 0 fiducials within COMM the area boundary. COMM COMM The local projection is a UTM projection based on the COMM WGS84 spheroid with a central meridian of 147 East degrees. COMM System parallax of 0.6 fiducial has been removed. COMM COMM MAGNETIC DATA COMM The magnetic data has been corrected for regional gradient by subtraction COMM of IGRF model 2005 computed continuously over the whole area based on COMM the GPS height. COMM Diurnal magnetic variations have been removed. COMM System parallax of 1.6 fiducial has been removed. COMM Tie-line levelling has been applied. COMM Microlevelling has been applied. COMM A base value of 61900 nT has been added to the data. COMM COMM RADIOMETRIC DATA COMM COMM Raw channel data provided has been energy calibrated COMM NASVD has been applied to channel data prior to windowing COMM System parallax of 0.0 fiducial has been removed. COMM Height attenuated to 80m AGL COMM Airborne radon has been removed COMM COMM AIRCRAFT BACKGROUND UNITS COMM Total Count 81.67 cps COMM Potassium 23.35 cps COMM Uranium 0.59 cps COMM Thorium 0.67 cps COMM COSMIC STRIPPING RATIOS COMM Total Count 0.811201 COMM Potassium 0.044663 COMM Uranium 0.038646 COMM Thorium 0.043791 COMM COMPTON STRIPPING RATIOS COMM alpha 0.250 COMM beta 0.400 COMM gamma 0.810 COMM a 0.060 COMM HEIGHT ATTENUATION COEFFICIENT COMM Total Count 0.006928 per metre COMM Potassium 0.009043 per metre COMM Uranium 0.007186 per metre COMM Thorium 0.006892 per metre COMM WINDOW ENERGY LEVELS Low Energy High Energy COMM Total Count 410.0 2810.0 keV COMM Potassium 1370.0 1570.0 keV COMM Uranium 1660.0 1860.0 keV COMM Thorium 2410.0 2810.0 keV COMM COMM DIGITAL TERRAIN MODEL DATA COMM COMM DIGITAL TERRAIN MODEL CALCULATION COMM The radar altimeter data was subtracted from the GPS heights to provide COMM a digital elevation model which is height above the WGS84 spheroid. Using COMM interpolation on the 120 second DMA Geoid model, a correction was computed COMM and subtracted from the WGS84 data to convert to height above the geoid. COMM COMM DATA RELIABILITY COMM This Digital Terrain Model (DTM) has been computed from data generated COMM during the course of an airborne geophysical survey flown at a nominal COMM spacing of 50m and data has been interpolated between such lines. COMM Every effort has been made to make this model a useful general reference. COMM No guarantee can be made that this model is a true representation of height COMM above sea level as it can contain radar altimeter responses from buildings COMM and in some instances dense timber. Users of the product should be aware COMM of the topographic limitations mapped herewithin. Do not use this DTM for COMM navigation purposes.