Exercise 02 Magnetic Compass

1. Start at 16T 0295794 4933525 (call this Point Y). How would you describe this location for persons who are not familiar with the UTM grid reference system? East door Science Building

2. At present (2004), the magnetic declination in Stevens Point is -1�40�. Rounding this declination to an even -2�, what is the magnetic azimuth to the NORTHEAST corner of the LRC [library] building? 191.5�T + 2� = 193.5�M

3. Now, suppose that there is a consistent deviation of �12.5� due to ceiling lights at Point Y, that it has been 30 years since the map publication indicating -2� declination, and that annual variation has averaged +10�. Under these circumstances, what is the true azimuth to the NORTHEAST corner of the LRC [library] building from Point Y? [-12.5� + (-2�) + ((+10')30yrs)/60)] = -9.5� + 193.5�M = 184�T

4. Now proceed to 16T 0295640 4933500 (Site 02). Here we shall perform the �Cumberland Rain Dance� to calibrate our magnetic compasses. That odd term derives from an English SAR team that devised a practice to check magnetic departures quickly on-site. Essentially, every compass reads known azimuths to landmark positions surrounding a site. The compass reading difference is deviation. Site 02 magnetic azimuths are: [NEXT]

J NE corner CPS	355�M	Your magnetic azimuth =	Deviation =
K SE corner CPS bay	297�M	Your magnetic azimuth =	Deviation =
L NW corner CNR	207�M	Your magnetic azimuth =	Deviation =
O NW corner Science	016�M	Your magnetic azimuth =	Deviation =
P SW corner Science	094�M	Your magnetic azimuth =	Deviation =

5. On the Thousand Springs ID quadrangle, what is the true azimuth from the benchmark BM3182 toward the north end of the powerhouse at 11T 0676786 4734457?

147.2�T - 14.8� = 132.5�M

6. You just completed an assignment at 11T 0677640 4733200. The coordinator at 11T 0676786 4734457 asks you to estimate what time you can get there. If you can walk at 1 km/hr (not unrealistic at all after a full day�s walk), what time should you estimate for your arrival if is now 9 AM, and what magnetic direction will you travel toward? ((1.52km x 1kph)60) = 91 min + 9 AM = 10:31 AM; 312.5�M (reciprocal of 132.5�M)

7. What probably is going to cause you to arrive late, and actually use a different azimuth?? The cliffs by the fish farm, and still more cliffs by the powerhouse

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