Meters per minute of longitude

In the morning the class worked on finding Binky. This term Binky was at North 6° 54.570', East 158° 09.337'. Binky was hidden in the tall grass at the bottom of a tree down a slope off the edge of campus. This led naturally to the question of just how close to Binky could the coordinates have put a searcher? Put another way, how far is 0.001 arc minutes in meters?

Laboratory seven sought to determine the conversion factor between meters and minutes. The conversion factor would allow one to convert 0.001 arc minutes to meters.

Julie-Ann Ardos with the surveyor's wheel

Spring 2015 I sought to decrease the error by using a more precise conversion between feet (measured by the surveyor's wheel) and meters. Rather than use 100 clicks on the non-metric surveyor's wheel as 30 meters, spring 2015 I went ahead and converted each 30 meter interval into feet: 98, 197, 295, 394, 492, and 591 feet. I then rolled the wheel while holding a crib sheet with the equivalents in feet.

Barry Diopulos watches the latitude in the rain

This summer I decided to run with the original 100 click design which is known to have about 1.5% error out at 600 feet. The 100 click rule (100 feet) allowed a student to take over the surveyor's wheel work.

Julie-Ann, wet but undeterred

The class started at 158° 09.600' east which made for easier subtraction of the start longitude. Visually the change in arc minutes is also easier to comprehend. 158° 09.000' would be better yet, but that is not on campus. This term a start at the "second palm" put the latitude at 6° 54.570'

Joemar Wasan, Barry, and Sharon Mualia watch their GPS units. Rain is falling harder, but they are undistracted

The rain chased away all but five students by the time we reached 600 feet (roughly 180 meters): Julie-Ann, Pelma Dilipy, Joemar, and Barry.

Sharon shows Pelma and Julie-ann her GPS readings

Barry and Joemar at 600 feet

The results of the data are close to the published value of about 1842 meters per minute. The slope is within 3% of the true value. 

On Friday the class took the midterm. Binky was there at the midterm.


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