Tuesday, May 24, 2011

Where on earth are you?

A geographic coordinate system is a coordinate system that enables every location on the Earth to be specified by a set of numbers. The numbers represent the exact latitude and longitudinal position. If you look at a Gps every object will have a specific position where a latitude and a longitude intersect,

Doesn’t matter where on the earth you find yourself, you will have a latitude and longitudinal position. In South Africa your latitude position will always be south (South Africa is positioned between 22˚ & 35˚ South and 16˚& 33˚ East). Your latitude reference will always be South and longitude reference East. E.g. 27˚38’27’’ S and 30˚18’49’’E.

How do I determine my coordinates on a topographic map?
 
As mentioned before you always give the latitude first and then the longitude.
Step 1: Identify the the object on the topographic map
As mentioned before you always give the latitude first and then the longitude.


Step 1: Identify the object on the topographic map

Step 2: Look at the top of the map and find the latitude (23˚S) and the longitude (33˚E).

Step 3: Find the minutes by looking at the latitude and longitude immediately above (17’) and to the left (25’) of the object. Your coordinate thus far is 23˚17’S and 33˚25’E

You are not yet done, as you need to calculate the seconds.

Step 4: In the grid block where your object is situated measure the following (see diagram)


Latitude: a ÷ A = answer x 60 = C

Longitude: b ÷ B = answer x 60 = D

Therefore, coordinate for spot is –

23˚17’C”South and 33˚25’D”East


 
Latitude: a ÷ A = answer x 60 = C''


Longitude: b ÷ B = answer x 60 = D''

Therefore, coordinate for spot is –

23˚17’C”South and 33˚25’D”East