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The Equation Of Time Chart

The following Equation of Time Chart can be used with your Petra Precision Sundial to convert the zonal solar time displayed on the sundial to standard clock time.  Note the current time displayed on your sundial, check the Equation of Time Chart and locate the current month and day of the year, trace up to determine the amount of minutes to add or subtract to the sundial’s time to convert to the standard clock time.  
You will note, there are 4 times during the year when the line intersects the “0” line on the chart. On these days, no correction is needed.  You are seeing current clock time on your sundial.

The Equation of time