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46 lines
1.4 KiB
46 lines
1.4 KiB
<sect2 id="calc-apcoords">
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<title
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>Apparent Coordinates module</title>
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<indexterm
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><primary
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>Tools</primary>
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<secondary
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>Astrocalculator</secondary>
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<tertiary
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>Apparent Coordinates module</tertiary>
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</indexterm>
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<screenshot>
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<screeninfo
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>The Apparent Coordinates calculator module </screeninfo>
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<mediaobject>
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<imageobject>
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<imagedata fileref="calc-apcoords.png" format="PNG"/>
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</imageobject>
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<textobject>
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<phrase
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>Apparent Coordinates</phrase>
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</textobject>
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</mediaobject>
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</screenshot>
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<para
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>The Apparent Coordinates module converts the <firstterm
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>catalogue coordinates</firstterm
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> of a point in the sky to its <firstterm
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>apparent coordinates</firstterm
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> for any date. The coordinates of objects in the sky are not fixed, because of <link linkend="ai-precession"
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>precession</link
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>, nutation and aberration. This module takes these effects into account. </para>
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<para
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>To use the module, first enter the desired target date and time in the <guilabel
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>Target Time/Date</guilabel
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> section. Then, enter the catalogue coordinates in the <guilabel
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>Catalog Coordinates</guilabel
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> section. You can also specify the catalogue's epoch here (usually 2000.0 for modern object catalogues). Finally, press the <guibutton
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>Compute</guibutton
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> button, and the object's coordinates for the target date will be displayed in the <guilabel
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>Apparent Coordinates</guilabel
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> section. </para>
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</sect2>
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