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+<sect2 id="calc-equinox">
+<title>Equinoxes and Solstices module</title>
+<indexterm><primary>Tools</primary>
+<secondary>Astrocalculator</secondary>
+<tertiary>Equinoxes and Solstices module</tertiary>
+</indexterm>
+
+<screenshot>
+<screeninfo>
+The Equinoxes and Solstices calculator module
+</screeninfo>
+<mediaobject>
+  <imageobject>
+    <imagedata fileref="calc-equinox.png" format="PNG"/>
+  </imageobject>
+  <textobject>
+    <phrase>Equinoxes and Solstices</phrase>
+  </textobject>
+</mediaobject>
+</screenshot>
+
+<para>
+The <link linkend="ai-equinox">Equinoxes</link> and 
+Solstices module calculates the date and time of an 
+equinox or solstice for a given year.  You specify which 
+event (Spring Equinox, Summer Solstice, Autumn Equinox, 
+or Winter Solstice) should be investigated, and the year.  
+Then press the <guibutton>Compute</guibutton> button to 
+obtain the date and time of the event, and the length of 
+the corresponding season, in days.
+</para>
+<para>
+There is a batch mode for this module.  To use it, simply 
+generate an input file whose lines each contain a year 
+for which the Equinox and Solstice data will be computed.  
+Then specify the input and output filenames, and press the 
+<guibutton>Run</guibutton> button to generate the output 
+file.  Each line in the output file contains the input year, 
+the date and time of each event, and the length of each 
+season.
+</para>
+</sect2>