1 files changed, 41 insertions, 0 deletions
diff --git a/doc/kstars/calc-apcoords.docbook b/doc/kstars/calc-apcoords.docbook
new file mode 100644
index 00000000..171eba09
--- /dev/null
+++ b/doc/kstars/calc-apcoords.docbook
@@ -0,0 +1,41 @@
+<sect2 id="calc-apcoords">
+<title>Apparent Coordinates module</title>
+<indexterm><primary>Tools</primary>
+<secondary>Astrocalculator</secondary>
+<tertiary>Apparent Coordinates module</tertiary>
+</indexterm>
+
+<screenshot>
+<screeninfo>
+The Apparent Coordinates calculator module
+</screeninfo>
+<mediaobject>
+  <imageobject>
+    <imagedata fileref="calc-apcoords.png" format="PNG"/>
+  </imageobject>
+  <textobject>
+    <phrase>Apparent Coordinates</phrase>
+  </textobject>
+</mediaobject>
+</screenshot>
+
+<para>
+The Apparent Coordinates module converts the <firstterm>catalog 
+coordinates</firstterm> of a point in the sky to its 
+<firstterm>apparent coordinates</firstterm> for any date.  The 
+coordinates of objects in the sky are not fixed, because of 
+<link linkend="ai-precession">precession</link>, nutation and
+aberration.  This module takes these effects into account.
+</para>
+<para>
+To use the module, first enter the desired target date and time 
+in the <guilabel>Target Time/Date</guilabel> section.  Then, 
+enter the catalog coordinates in the <guilabel>Catalog 
+Coordinates</guilabel> section.  You can also specify the 
+catalog's epoch here (usually 2000.0 for modern object 
+catalogs).  Finally, press the <guibutton>Compute</guibutton>
+button, and the object's coordinates for the target date 
+will be displayed in the <guilabel>Apparent Coordinates</guilabel>
+section.
+</para>
+</sect2>