# Lab Write-up for Group Purple

## Introduction

Our task was to find the Latitude and Longitude of the Greenwich Theater using three different methods. We were also tasked with finding the elevation and distance to the Prime Meridian using two different methods, and what was due south and North of the location. Here is the methods we used to find the information.

• Latitude
• Reasonable Guess
• Using a picture taken off Google Earth with two known degrees of latitude, then estimating where our location lies between them
• GPS
• Longitude
• Reasonable Guess
• Figure out the distance to the PM, convert the linear measurement to degrees longitude, then add or subtract that from the 0 degrees (The PM)
• GPS
• Elevation
• GPS
• Distance to Prime Meridian
• GPS track feature
• Due South
• Compass
• Due North
• Compass

The Greenwich Theater was located several hundred meters from the Thames and had its back to the Royal Naval College. While the theater itself is fairly large, we were only concerned with the front entrance which was a small awning overlooking a fairly quiet street. The Rose and Crown Pub was next door, which happened to be due North of the entrance. The Fan Museum was due South.

## Data Collection

• Latitude
• Reasonable Guess:57.45
• GPS: 51.47937
• Longitude
• Reasonable Guess:-0.00171
• GPS: -0.00804
• Elevation
• GPS:10.05 M
• Distance to Prime Meridian
• GPS track feature:121 Meters
• Due South
• Fan Museum
• Due North
• Rose and Crown Pub

## Data Analysis

• GPS - according to the Garmin website, our GPS, the Etrex Vista C, is accurate within 30 meters 95% of the time. After importing our points to Google Earth, it looks like our points are within a tighter range. If the GPS has been calibrated, it is supposed to calculate the elevation within 3 meters of accuracy.
• Google Earth - Google Earth's elevation is typically within +_ 10 meters. We were unable to find out the accuracy of the latitude and Longitude settings, however they do offer a disclaimer say it is not accurate navigation. Several websites claimed that it is hard for Google Earth to be accurate due to how they map the area and how they stitch the various photos together.
• Reasonable Guess - this was not very accurate, especially when we did the calculations using the distance from the PM converted to degrees to calculate the Longitude.
• Compass - This was very accurate because we were looking at big targets. For instance, the Rose and Crown pub, situated five meters away occupied several degrees away from due North, so even if were were significantly off we would still have come up with the same result.

## Results

Using a variety of methods we were able to return a variety of results. Generally the newer the technology the better it was. Obviously our guesses lacked the accuracy of the GPS and Google Earth. Interestingly enough, Google Earth is not noted for its accuracy for a variety of reasons including updates in the software used to stitch it together. The GPS was the only tool with readily available data on its accuracy and it did not turn out to be that precise. We do not have any raw data, we will make sure to collect it in the future.

## Extra Credit

File:Earthlab.pdf Extra Credit

Reviewed - 21 February 2011