Depending on your source of information, Boston, Massachusetts is located at
| "422016N0710107W" 15-character WGS84
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| "42.33602 N, -71.01789 W" Degree / Decimal
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| "42º 20.1612', -71º 1.0734''" Degree / Minute / Decimal
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| "42º 20' 9.67" N, 71º 1' 4.4" W" Degree / Minute / Second
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| "19 333761 468097" UTM (Universal Transverse Mercator grid)
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As with all technical areas requiring absolute precision and rationality, there are rabid defenders of each type of expression who get into red-faced, acrimonious shouting matches with rabid defenders of other types.
When you create a new map, Robin Lovelock says that 15-character WGS84 notation is the recommended one for GPSS.
Take the 15-character WGS84 location for Boston 422016N0710107W:
| Split this into its 2 components:
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| "422016N" = 42 degrees 20.16 minutes N
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| "0710107W" = 71 degrees, 1.07 minutes W
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You'll also see that certain positions are padded with a leading 0 (zero) or two.
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Some use the Degree / Minute / Second format. If you were to head west and circumnavigate the world and stop just short of where you started, in this notation you traveled westward (and longitudinally):
| 359 degrees 59 minutes and 59 seconds.
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In 15-character WGS84, that would be:
| 359 degrees 59.98333 minutes.
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In Degree / Decimal notation, this would be
| 359.999722 degrees.
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| NOTE: you can use degree / decimal location (such as you find at the US Census Gazetteer) when designating points on maps imported into GPSS.
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| Just be sure to use leading 0s (zeros) when needed - see the end of this topic.
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See the Geographical Formats Understood by GPSS (a reorganization of the material on the GPSS site).
Translating from one to another
If you want to translate from one expression type to another, you can figure out the math yourself, or find an online coordinate translator. The Jeeep site has one at http://www.jeeep.com/details/coord (note the 3 e's in the name), but like all things Internet, this might go away.
| To find an online translator of your own, do an online Internet search for "WGS84 coordinate translator" or "WGS84 coordinate translation"
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Translating from one format to another
Once you have found an online translator to get from, say, decimal to 15-character, there are 3 additional details:
| 1. | Degrees W in many notations will be - (minus) degrees
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| 2. | For latitude minutes, GPSS wants 2 digits, padded with a leading zero if less than 10 (e.g., 1 minute = 01)
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| 3. | For longitude, GPSS wants 3 digits for degrees, padded with leading zeros if less than 100 degrees. Thus, -71 becomes 071.
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Example from one online translator
On the online translator at the Jeeep site, you can, for example, enter the U.S. Gazetteer numbers under Degree Decimal.
| 1. | Latitude is 42.33602
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| 2. | Longitude is -71.01789
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When you press Submit, you'll see a table of answers - two tables, if the location you enter is in the United States, where 2 different systems can be found (2 systems with discrepancies as much as 200 meters.)
Use the figures you find under MinDec in the table for WGS48 (NAD 83):
43 degrees 20.1612 minutes
-71 degrees 1.134 minutes
Or, as you see it at the Jeeep site:
You then note this as 432016N0710113W in GPSS.
Be sure to add leading 0s.
| In GPSS, North-South degrees are always 2 characters (to accommodate the maximum of 90)
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| East-West degrees are always 3 characters (to accommodate the maximum of 360)
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By Dave Gehman
© Copyright 2004, Robin Lovelock
Send changes, suggestions to Dave Gehman