STAR*NET V6 - Circe

Chapter 10 Adjustments in Grid Coordinate Systems
10.7 Selecting a UTM Zone
Universal Transverse Mercator (UTM) zones cover the earth in 6 degree zones, starting
with Zone 1 which spans 180 West to 174 West, and increasing eastward to Zone 60
which spans 174 East to 180 East.
To select a UTM zone, choose UTM from the Grid selection dropdown selection list
previously shown and the zone selection dialog will automatically appear. Or if UTM is
already selected, simply press the large zone list button to select a new zone.
In the zone selection dialog, choose a zone number from 1 to 60 by either typing the
number in the UTM Zone field, or by scrolling the zone numbers using the arrows. As
you change the numbers in the zone field, the zone boundaries will be displayed to help
you verify that you entered the correct zone number.
For example, to select a zone that would include Oakland, California, which has a
longitude of approximately 123 degrees west, you would select UTM zone 10 which
spans between 120 and 126 west of Greenwich as illustrated above.
By default, the GRS-80 ellipsoid is initially selected. To select a different ellipsoid,
select one from the dropdown selection list and its parameters will be displayed.
Also by default, the Northern Hemisphere is initially selected. If you are working in an
area south of the equator, select the South Hemisphere radio button.
Finally, press OK to actually choose the zone and exit the selection dialog.
Note that values for latitudes in your data should not be used beyond 80 or -80 degrees in
the north and south hemispheres respectively.
Also as mentioned earlier in this chapter, always to use proper signs for latitudes and
longitudes in your data! Use positive latitudes for points north of the equator, and
negative latitudes for points south of the equator. And for longitudes, use signs based on
the “Longitude Sign Convention” selected in the Project Options/General dialog.
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