Mapping Toolbox    

Time Notation

Navigational practice has its own peculiar notation for times. Time labels on navigation plots are always in a special format. Times are given in four digits, hours from 00 to 23 followed by minutes from 00 to 59. So, one minute before noon is 1159, or 1159Z or 1159Q, etc., based on time zone. Similarly, one minute after midnight is 0001. When more precision is required, the seconds are rounded to the nearest quarter minute and zero, one, two or three apostrophes are suffixed to the time, one for each 15-second block. So, 15 seconds before noon would be 1159'''; 14 seconds before noon would have the exact same notation.

The Mapping Toolbox includes the function time2str that returns a string in a variety of formats corresponding to a given time. These strings can then be plotted on map displays as desired. Two other clock formats are also allowed - the 12-hour and the 24-hour digital clock readouts. Consider some string notations for the time 13.21 hours after midnight. The default 24-hour clock is:

The 12-hour clock reads:

And the navigation format for this time is:

Each of these can be rounded to the nearest minute with the third argument 'hm' (for hours-minutes - the default is 'hms'):


  Time Zones GUI Tools