<sect2 id="calc-angdist">
<title
>Angular Distance module</title>
<indexterm
><primary
>Tools</primary>
<secondary
>Astrocalculator</secondary>
<tertiary
>Angular Distance module</tertiary>
</indexterm>

<screenshot>
<screeninfo
>The Angular Distance calculator module </screeninfo>
<mediaobject>
  <imageobject>
    <imagedata fileref="calc-angdist.png" format="PNG"/>
  </imageobject>
  <textobject>
    <phrase
>Angular Distance</phrase>
  </textobject>
</mediaobject>
</screenshot>

<para
>The Angular Distance tool is used to measure the angle between any two points on the sky. You simply specify the <link linkend="equatorial"
>Equatorial coordinates</link
> of the desired pair of points, and then press the <guibutton
>Compute</guibutton
> button to obtain the angle between the two points. </para>
<para
>There is also a Batch mode for this module. In batch mode, you specify an input filename which contains four numbers per line: the RA and Dec values for pairs of points. Alternatively, you can specify a single value for any of these four coordinates in the calculator panel (the corresponding values in the input file should be skipped if they are specified in the calculator). </para>
<para
>Once you have specified the input filename and an output filename, simply press the <guibutton
>Run</guibutton
> button to generate the output file. </para>
</sect2>
