Decimal Vs Sexagesimal Notation
Traditionally sexagesimal notation (degrees, minutes, and seconds) has
been used to describe geographical location. More recently decimal
degrees have become popular because of their ease of use in calculations
and information technology. Almost all GPS devices and internet
applications such as Google Earth, Earth Tools and Wikimapia have the
option of using decimal degrees.
The International Standard for the standard representation of latitude
and longitude has recently been revised (ISO 6709 - 2008). Sexagesimal
notation is still allowed but decimal degrees are now the preferred
method of specifying a geographical location. Latitude is given by a
number between +90 and -90. Longitude is a number between +180 and -180.
The number of decimal places quoted gives an indication of the precision
of the measurement. Two places imply a precision of around 1km. Five
decimal places indicate a precision of around 1m.
May I suggest to the Australian Birding Community that perhaps it is now
time to address the question of how we specify geographical location.
The main application concerned is atlassing, both at the Birds Australia
level and local club level. The current atlas forms have boxes for
degrees, minutes and seconds but could be easily modified to include a
decimal point.
Sexagesimal notation has been around a long time, since Sumerian and
Babylonian times in fact. However I suggest that it is now time to use a
simpler and more convenient method of describing location.
Those of us who still lament the passing of pounds, shillings and pence
and quarters, pounds and ounces may resist changing but I am sure most
birders will welcome this change.
Jim Smart
East Maitland
-32.7531+151.5884
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