Longitude and latitude can be used to determine the exact location of a point on the surface of a globe. There are several ways to find the longitude and latitude of your location, and some methods require more resources than others. Find your coordinates using a map and a protractor after understanding longitude and latitude well.
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Method 1 of 3: Understanding Longitude and Latitude
Step 1. Understand about latitude
Latitude measures how far a point is north or south of the equator from that line. Since the earth is spherical, the distance from the equator is measured in angular degrees, i.e. the equator is 0 degrees latitude and the north pole which is the northernmost point of the earth is at 90 degrees. The south pole, which is the southernmost point of the earth, is also at 90 degrees.
Latitude is measured in degrees north latitude when the point is in the northern hemisphere, and degrees south latitude when the point is in the southern hemisphere
Step 2. Understand longitude
Longitude measures the distance of a point east or west of the prime meridian, which is defined to be Greenwich, England. Since the earth is spherical, the distance from the prime meridian is measured in angular degrees with the prime meridian defined as 0 degrees longitude. As you move east or west, longitude measures the distance to 180 degrees from the prime meridian.
- 180 degree longitude is known as the international dateline.
- Longitude is measured in degrees east longitude if the point is in the eastern hemisphere, and is measured in degrees west longitude if the point is in the western hemisphere.
Step 3. Know the accuracy of your measurements
Degrees are a large unit of measurement so in order to be able to locate locations accurately, longitude and latitude are separated by a decimal point, also known as decimal degrees. For example, you can view the location of a point as 35, 789 north latitude. Global Position Systems (GPS) usually display this decimal point, but printed maps do not.
Online topographic maps express decimal degrees of longitude and latitude in degrees, minutes, and seconds. Each degree equals 60 minutes, and every minute equals 60 seconds. This comparison against time allows for easier subdivision
Step 4. Understand the display of longitude and latitude on the map
First of all, always assume that the top of the map is north. The number on the right and left side of the map is the latitude. The numbers at the top and bottom of the map are longitudes.
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Don't forget to convert the latitude/longitude numbers on the map using decimal degrees to time in degrees, minutes, and seconds format.:
- 15 seconds = 1/4 minute = 0.25 minutes
- 30 seconds = minutes = 0.5 minutes
- 45 seconds = minutes = 0.75 minutes
Method 2 of 3: Using Maps
Step 1. Get a map with the Indonesian National Standard (SNI)
Maps with Indonesian National Standards are produced by the Geospatial Information Agency under the Indonesian government. You can find them at the downtown library, or buy them from surveyors or other commercial stores.
Step 2. Find longitude and latitude
This unit of measurement is usually the corner of the map. Under the heading, you can also find out how far the map is covered. For example, a map may say that the distance is 7.5 minutes on the map, which means that the area the map shows covers 7.5 minutes of longitude and latitude.
Step 3. Find the location
Depending on the scale of your map, it may take some time to find your location. Pay attention to the specific city or point on the map that shows your current position. Once found, mark your location. The map legend will tell you the scale of the map so you can quickly estimate the relative distance to a particular location, if you don't know the name of your city. This method helps you find your location faster.
Depending on the location you're looking for, make sure you're using a map that's appropriately scaled. If you want to find the distance of a province from yours, we recommend using the island map instead of the Indonesia map or the world map
Step 4. Use the map ruler to check the degrees
Measure the distance from your location off the map to the straightest numbered latitude or longitude. The map will be divided into vertical and horizontal lines representing the longitude and latitude. The four corners of the map will display the longitude and latitude coordinates. For all dots in between, only the last two digits will be displayed.
- Your map should have latitudes and longitudes that form a “grid” and divide it into four opposite sections. Have a map ruler ready as it is easy to use and can be purchased at bookstores, outdoor supply stores, or online. Make sure the map ruler matches the 1:24,000 scale map.
- Measure the latitude first. The latitudes will align north and south of your location. Place the zero end of the map ruler at south latitude. The next latitude is parallel to the north and must be touched by the 2 minute mark on the ruler. One edge of the ruler will be marked in minutes and seconds while the other edge will be in decimal minutes. Make sure you use the correct edges and match the coordinate format of your map. Slide the ruler right, or west, until it hits your location. Mark the distance between south latitude and your location. Add the measured number with southern latitude to get the latitude of your location.
- To measure longitude, you must place a ruler diagonally on the west and east meridians, and touch the ends of the 2 minute ruler on both meridians. The lines of longitude on the map will be the east and west meridians of your location. You must measure diagonally because the ruler extends across the grid if measured horizontally. This is because the meridians of longitude get closer as they get further away from the equator. Move the ruler vertically until you find your location while making sure both ends of the ruler are on the meridian in a diagonal position. Record your location in minutes and seconds, west of the east meridian. To find the longitude of your location, add the obtained number to the longitude of the east meridian.
Step 5. Record your coordinates
According to standard procedure, latitude is written first, then longitude followed, and both have as many decimal places as possible. The more numbers after the decimal point, the more accurate and precise your location will be
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When writing down coordinates, you can record longitude and latitude in three ways::
- Degrees (d.d°) – 49, 5000°, -123, 5000°
- Minutes (d°m.m') - 49°30.0', -123°30.0'
- Seconds (d°m's) - 49°30'00"N, 123°30'00"B
- When dealing with longitude and latitude, the words North, South, East and West are not used and are replaced with the negative symbol (-) for points south of the equator.
Method 3 of 3: Measuring Using a Protractor
Step 1. Make sure the measurements are taken in daylight
Determining latitude using the sun can only be done when the sun is at its highest point. Check your watch or use the method to create a quadrant and place the stick on the ground, at the southernmost end of the north-south line. The sun is at its peak when the stick shadow covers the north-south line.
Use a plumb line to make sure the sticks are standing vertically. Plumb line (pendulum rope) is exactly as the name suggests, namely a rope attached to a pendulum of any type. The rope will be kept vertically upright with the help of gravity
Step 2. Use the compass to determine the north and south directions
You can only do this if you know the direction north and south. Mark the north and south directions by making a long line on the ground. Create a quadrant by adjusting the aiming block so that it is parallel to this line.
Step 3. Make a quadrant, or cross, using two sticks
The aiming beam, or cross section of the arms, must be installed exactly in the center of the support beam, which forms part of the body of the cross mark. Put a nail at each end of the aiming beam, and make it far enough apart so that it is stable. You will need to attach 2 nails to the face of each end of the beam and 2 nails to the top of each end of the beam.
Center the protractor at the pivot point. Also hang the pendulum string at this pivot point
Step 4. Align the nails in the beam with the sun
When the sun is at its peak, align the spikes of the beam with the sun. Don't look directly at the sun, but use the shadow of the spikes to find the right position. Raise and lower the aiming beam so that the two shadows from the spikes come closer and create a single shadow on the ground.
Step 5. Use a protractor to measure the sharp angle between the aiming beam and the pendulum string
Once the block is properly placed, use a protractor to measure the angle between the pendulum string hanging vertically and the hand of the aiming block closest to the pendulum. Try to keep the horizon at 90 degrees when you take your measurements.
Step 6. Understand that the choice of time can affect the accuracy of the measurement results
Your measurement results are only correct if the times of day and night in spring and fall are the same (equinox), which is March 21 and September, respectively. If you measure around December 21, or in the middle of winter, subtract 23.45 degrees from the measurement result. Conversely, add 23.45 degrees if the measurement is taken around midsummer, i.e. June 21
- Your measurements aren't completely accurate, except for the spring and fall equinoxes because the earth tilts slightly in its orbit around the sun.
- While there are complex tables that provide precise factors for determining the exact longitude and latitude of your location on any given day, forecasts are fairly accurate using dates relative to the spring and fall equinoxes. For example, if you take your measurements in early May, halfway between spring (when the sun is directly over the equator) and the summer equinox (when the sun is above 23.45 degrees north of the equator, you only need to add 23.45 degrees. (11, 73) on the measurement results.
Tips
- The online calculator can also be used as a simple way to calculate longitude and latitude.
- You can download mobile device applications to help determine the longitude and latitude of a location, including GPS applications.
