<sect2 id="calc-sidereal">
<title
>Sidereal Time module</title>
<indexterm
><primary
>Tools</primary>
<secondary
>Astrocalculator</secondary>
<tertiary
>Sidereal Time module</tertiary>
</indexterm>

<screenshot>
<screeninfo
>The Sidereal Time calculator module </screeninfo>
<mediaobject>
  <imageobject>
    <imagedata fileref="calc-sidereal.png" format="PNG"/>
  </imageobject>
  <textobject>
    <phrase
>Sidereal Time</phrase>
  </textobject>
</mediaobject>
</screenshot>

<para
>This module converts between <link linkend="ai-utime"
>Universal Time</link
> and Local <link linkend="ai-sidereal"
>Sidereal Time</link
>. First, select whether you will use Universal Time or Sidereal Time as an input value in the <guilabel
>Input Selection</guilabel
> section. You must also specify a geographic longitude, and a date for the calculation, in addition to either the Universal Time or the Sidereal Time value. When you press the <guibutton
>Compute</guibutton
> button, the corresponding value for the other Time will be displayed. </para>
</sect2>