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Maps, Charts and Coordinate Systems

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FA map is a two-dimensional representation of the Earth. FMaps incorporate projections and datums for accuracy. FAll maps distort the earth to some extent. FWhen using a map with a GPS receiver, the datum and coordinate system must match. Maps

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DeLorme Gazetteer - 1:65,000 to 1:400,000 1” = 1.0 miles to 6.3 miles (Scale varies by state) Map and Chart Scales CBSAR uses this

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Projecting a Sphere Onto a Plane

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Plane Projection Cylindrical ProjectionConical Projection Types of Projections

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Accurate Shapes Accurate Sizes Exaggerated Sizes Distorted Shapes Types of Projections

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Meade Ranch (Clarke 1866) Map Projections

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FAll coordinate systems reference some particular set of numbers for the size and shape of the earth (the datum). FCoordinates designate locations within a spatial reference system (datum). FThere are two types of global coordinate systems: FAngular Coordinates FRectangular (Cartesian) Coordinates FLatitude and longitude, and Universal Transverse Mercator are two global coordinate systems used by GPS. FMany other coordinate systems exist worldwide. Coordinate Systems

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FA spherical coordinate system that is unprojected. FAngular coordinates are perfectly suited to the spherical surface of the earth. FCoordinates are expressed in degrees, minutes and seconds (and variations of that). FPosition coordinates are based on an angular distance from a known reference point. FThe intersection of the Prime Meridian and Equator. FLat/long is the predominant coordinate system used for nautical and aeronautical navigation. Latitude & Longitude

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0º 0º Point of Origin Prime Meridian Equator (Longitude) (Latitude) 10º N 30º N 10º S

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FLatitude is comprised of parallels, which are circles around the earth paralleling the Equator. FParallels are designated by their angle north or south of the Equator. FThe Equator is 0º latitude, and the North and South Poles are at 90º angles from the Equator. FThe linear distance between parallel lines never changes, regardless of their position on earth. F1 minute of latitude = 1 nautical mile = 6076 feet F1 degree of latitude = 60 nautical miles = 69 statute miles Latitude

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Parallels of Latitude 10º

15
10º 10º 10º 690 statute miles 10º S 0º N 10º N 20º N Parallels of Latitude 690 statute miles Crested Butte is 38 o N of the Equator

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FLongitude is comprised of meridians that form one-half of a circle. FMeridians are designated by their angle west or east of the Prime Meridian. FThe Prime Meridian is designated 0º and extends from the North Pole to the South Pole through Greenwich, England. FMeridians are angled, and do not parallel each other. FThe linear distance between one degree of longitude at the Equator is approximately 69 statute miles. FThe linear distance between one degree of longitude at the Arctic Circle is about 26 statute miles. Longitude

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Meridians of Longitude 10º

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10º 10º 110º W 120º W 690 miles 460 miles 240 mi 10º Equator Meridians of Longitude

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Determining Latitude & Longitude 30º N 50º W Equator (0º) Prime Meridian (0º) 30ºN, 50ºW

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Lat/Lon Coordinates hddd 0 mm’ ss.s”: N 43 0 40’ 55.8” X W 116 0 17’ 14.1” (55.8”)Degrees Minutes Seconds (55.8” / 60 =.93’) Degrees Minutes Seconds Different coordinates representing the same location: hddd 0 mm.mmm’: N 43 0 40.93’ X W 116 0 17.235’ (40.93’ / 60 =.68216 0 ) Degrees Decimal Minutes hddd.ddddd 0 : N 43.68216 0 X W 116.28725 0 Decimal Degrees

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Exercise Please do this quick exercise and then go to the next slide to see the answer.

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Here is an actual map. Write the latitude point for the top of Round Mountain in both decimal and second format on a piece of paper. The answer is on the next slide. 38 o 47.000’

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N 38 o 46.8’ N 38 o 46’48”

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Team Computer The previous exercise was made on the team computer. We added grids to make it easier for you. The normal 2.5 grid map is more difficult to use to estimate positions. Following is a map similar to those found in the cache.

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Latitude and Longitude 2.5’ = 2’ 30” (x3) 2.5 minute= 2.5’ = 2’ 30” (x 3) Grid is narrower at top than bottom Since there are (3) 2.5’ grids in each direction, these are called 7 1/2 minute topos or quads USGS 1:24,000 topographic map It is difficult to quickly determine or even estimate position in lat/lon BUT aircraft operate using lat/lon

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Latitude and Longitude With computer & software we can add grids to make it easier We can plot exact locations or eyeball it Let’s practice Go to next slide

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Latitude and Longitude With computer & software we can add grids to make it easier We can plot exact locations or eyeball it Let’s practice Write down the Lat. & Long. of the intersection of the two roads. Only do it to 1/10 of a minute accuracy. e.g. N 38 o 53.1’

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Latitude and Longitude With computer & software we can add grids to make it easier We can plot exact locations or eyeball it Let’s practice Answer N 38 o 53.4’ W 106 o 58.4’ If you were within.1’ of the above answer, you did great!

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FDo not read off just the numbers – use the words degrees, minutes and seconds as appropriate FRead 104º 54.9’ as one hundred four degrees fifty four point (or decimal) nine minutes FRead 104º 54’ 55” as one hundred four degrees fifty four minutes fifty five seconds Reporting Lat/Lon Coordinates

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Latitude and Longitude 2.5’ = 2’ 30” (x3) 2.5 minute= 2.5’ = 2’ 30” (x 3) Grid is narrower at top than bottom Since there are (3) 2.5’ grids in each direction, these are called 7 1/2 minute topos or quads USGS 1:24,000 topographic map It is difficult to quickly determine or even estimate position in lat/lon BUT aircraft operate using lat/lon To use our team maps, you need tools as follows

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Determining Latitude 44º 15’ 00” 17’ 30” 2.5 min Latitude of red square = 44º 16’ 48” Latitude Lines (Parallels) LATITUDE LONGITUDE 7.5 min. scale 1:24,000

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Determining Longitude Longitude of red square = 115º 19’ 00” 115º 17’ 30” 20’ 2.5 min Longitude Lines (Meridians) LATITUDE LONGITUDE 7.5 min. scale 1:24,000

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End of Lat. & Long. Section Next section will be UTM Universal Transverse Mercator

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