		AIRBORNE GEOPHYSICAL DATA

			

Survey name:			ARN Project
Location:			Yukon, Canada
Job No.:                        8077
Client:                         Archer Cathro & Associates Ltd. 
Survey date:     		June 16th to June 22nd, 2008
Survey company name:            Geotech Ltd.
Total line-km:                  221
Archive creation date:		November, 2008 

Aircraft type:                  ASTAR B3 helicopter, registration C-GTRK
Base of operation:              Dawson City, Yukon, Canada
 
Airborne Magnetometer
Model:				Geometrics 
Type:				Cesium-vapour
Sample Interval:		10 Hz (0.1 seconds); 2-3 metres
Sensitivity:			0.02 nT
Mount:                          Towed bird, 13 metres below helicopter
Height above ground:		59 metres

Airborne EM
Model:				Geotech Ltd. 
Type:				VTEM
Number of channels:		25 (0.120 - 9.245 ms) 
Sample Interval:		10 Hz (0.1 seconds); 2-3 metres
Mount:				Towed ring, 42 metres below helicopter
Transmitter Loop diameter:	26 m
Transmitter Number of turns:	4
Current:			262 Amp
Peak Dipole moment:		556,400 nIA
Pulse width:			4.2 ms
Receiver Loop diameter:		1.2 m
Receiver number of turns:	100
Receiver effective area:	113.1 m2
Height above ground:		36 metres

The VTEM decay sampling scheme is shown in table 3. Twenty-six measurement 
gates were used in the range from 120 ms to 9245 ms, as shown in Table 5.

	Table 3  Decay Sampling Scheme
VTEM Decay Sampling scheme
Array	( Microseconds )
Index	Time Gate	 Start	End	Width
0	0			
1	10		 10	21	11
2	21		 16	26	11
3	31	 	 26	37	11
4	42		 37	47	11
5	52		 47	57	10
6	62		 57	68	11
7	73		 68	78	11
8	83		 78	91	13
9	99		 91	110	19
10	120		 110	131	21
11	141		 131	154	24
12	167		 154	183	29
13	198		 183	216	34
14	234		 216	258	42
15	281		 258	310	53
16	339		 310	373	63
17	406		 373	445	73
18	484		 445	529	84
19	573		 529	628	99
20	682		 628	750	123
21	818		 750	896	146
22	974		 896	1063	167
23	1151		 1063	1261	198
24	1370		 1261	1506	245
25	1641		 1506	1797	292
26	1953		 1797	2130	333
27	2307		 2130	2526	396
28	2745		 2526	3016	490
29	3286		 3016	3599	583
30	3911		 3599	4266	667
31	4620		 4266	5058	792
32	5495		 5058	6037	979
33	6578		 6037	7203	1167
34	7828		 7203	8537	1334
35	9245		 8537	10120	1584

        

Mean terrain clearance:         72 m
Navigation type:		NovAtels CDGPS enable OEM4-G2-3151W GPS 
				(on the tail of the helicopter)
Radar altimeter: 		Terra TRA3000/TRI-40



Survey block	Traverse/Tie Line spacing (m)	Area (Km2)	Line-kms	Flight direction	Line numbers

ARN		Traverse: 100			20		 195		 N 0° E		 	L1500  L2120
		Tie: 950					 28		 N 90°E			T2200  T2250


		 

	AIRBORNE GEOPHYSICAL DIGITAL ARCHIVES


There are two (2) main directories:

	Data		contains databases, grids and maps, as described below.
			 	 			 
	Report		contains a copy of the report and appendixes in PDF format.


Channel Name	Description

X:		X positional data (meters  NAD83, UTM zone 7 north)
Y:		Y positional data (meters  NAD83, UTM zone 7 north)
Lon:		Longitude data (degree - NAD83, UTM zone 7 north)
Lat:		Latitude data (degree - NAD83, UTM zone 7 north)
Z:		GPS antenna elevation (meters - ASL)
Date		Flight Date (DD/MM/YYYY)
FltNo		Flight Number
Radar:		Helicopter terrain clearance from radar altimeter (meters - AGL)
RadarB:		EM Bird terrain clearance from radar altimeter (meters - AGL)
DEM:		Digital elevation model (meters)
Gtime1:		GPS time (seconds of the day)
Mag1:		Raw Total Magnetic field data (nT)
Mag2		Total Magnetic field diurnal variation corrected data (nT)
Mag3		Total Magnetic field final microlevelled data (nT)
Basemag:	Magnetic diurnal variation data (nT)
SF[10] = 0.120 millisecond time channel, pV/Am^4
SF[11] = 0.141 millisecond time channel, pV/Am^4
SF[12] = 0.167 millisecond time channel, pV/Am^4
SF[13] = 0.198 millisecond time channel, pV/Am^4
SF[14] = 0.234 millisecond time channel, pV/Am^4
SF[15] = 0.281 millisecond time channel, pV/Am^4
SF[16] = 0.339 millisecond time channel, pV/Am^4
SF[17] = 0.406 millisecond time channel, pV/Am^4
SF[18] = 0.484 millisecond time channel, pV/Am^4
SF[19] = 0.573 millisecond time channel, pV/Am^4
SF[20] = 0.682 millisecond time channel, pV/Am^4
SF[21] = 0.818 millisecond time channel, pV/Am^4
SF[22] = 0.974 millisecond time channel, pV/Am^4
SF[23] = 1.151 millisecond time channel, pV/Am^4
SF[24] = 1.370 millisecond time channel, pV/Am^4
SF[25] = 1.641 millisecond time channel, pV/Am^4
SF[26] = 1.953 millisecond time channel, pV/Am^4
SF[27] = 2.307 millisecond time channel, pV/Am^4
SF[28] = 2.745 millisecond time channel, pV/Am^4
SF[29] = 3.286 millisecond time channel, pV/Am^4
SF[30] = 3.911 millisecond time channel, pV/Am^4
SF[31] = 4.620 millisecond time channel, pV/Am^4
SF[32] = 5.495 millisecond time channel, pV/Am^4
SF[33] = 6.578 millisecond time channel, pV/Am^4
SF[34] = 7.828 millisecond time channel, pV/Am^4
SF[35] = 9.245 millisecond time channel, pV/Am^4
BF[10] = 0.120 millisecond time channel, pV*ms/Am^4
BF[11] = 0.141 millisecond time channel, pV*ms/Am^4
BF[12] = 0.167 millisecond time channel, pV*ms/Am^4
BF[13] = 0.198 millisecond time channel, pV*ms/Am^4
BF[14] = 0.234 millisecond time channel, pV*ms/Am^4
BF[15] = 0.281 millisecond time channel, pV*ms/Am^4
BF[16] = 0.339 millisecond time channel, pV*ms/Am^4
BF[17] = 0.406 millisecond time channel, pV*ms/Am^4
BF[18] = 0.484 millisecond time channel, pV*ms/Am^4
BF[19] = 0.573 millisecond time channel, pV*ms/Am^4
BF[20] = 0.682 millisecond time channel, pV*ms/Am^4
BF[21] = 0.818 millisecond time channel, pV*ms/Am^4
BF[22] = 0.974 millisecond time channel, pV*ms/Am^4
BF[23] = 1.151 millisecond time channel, pV*ms/Am^4
BF[24] = 1.370 millisecond time channel, pV*ms/Am^4
BF[25] = 1.641 millisecond time channel, pV*ms/Am^4
BF[26] = 1.953 millisecond time channel, pV*ms/Am^4
BF[27] = 2.307 millisecond time channel, pV*ms/Am^4
BF[28] = 2.745 millisecond time channel, pV*ms/Am^4
BF[29] = 3.286 millisecond time channel, pV*ms/Am^4
BF[30] = 3.911 millisecond time channel, pV*ms/Am^4
BF[31] = 4.620 millisecond time channel, pV*ms/Am^4
BF[32] = 5.495 millisecond time channel, pV*ms/Am^4
BF[33] = 6.578 millisecond time channel, pV*ms/Am^4
BF[34] = 7.828 millisecond time channel, pV*ms/Am^4
BF[35] = 9.245 millisecond time channel, pV*ms/Am^4
PLM:		60 Hz power line monitor


Electromagnetic B-field and dB/dt data is found in array channel format between 
indexes 10  35, as described above.


Database VTEM_waveform.gdb in Geosoft GDB format, containing the following channels:

	Time:		Sampling rate interval, 10.416 microseconds
	RX_Volt:	Output voltage of the receiver coil (volt)
	TX_Curr:         Output current of the transmitter (amps)

	
Grids in Geosoft GRD format, as follow,

	mag3_GK:		Total magnetic intensity (nT)
	BF25_GK:	        B-Field Channel 25 (Time Gate 1.641 ms)
	


A Geosoft .GRD file has a .GI metadata file associated with it, containing grid projection 
information. A grid cell size of 25 meters was used for the grids.


Maps at 1:10,000 scale in Geosoft MAP format, as follow,
 
	 VTEM B-field profiles, Time Gates 0.234  9.245 ms in linear - logarithmic scale, with TMI colour image.
	 VTEM dBdt profiles, Time Gates 0.234  9.245 ms in linear  logarithmic scale.
	 Total Magnetic intensity colour image and contours.
	 VTEM B-Field Time Gate 1.641 ms colour image.

	Maps are also provided in PDF format.


Google Earth files 8077_ARN_fltpath.kml showing the flight path of the test lines.

	Free version of Google Earth software can be downloaded from, 
	http://earth.google.com/download-earth.html


 
Flown and processed by:			Geotech Ltd.
					245 Industrial Parkway North
					Aurora, Ontario, L4G 4C4
					Phone: 905.841.5004
					Fax:   905.841.0611
					www.geotech.ca
					November 2008