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 <sect1 id="tool-aavso">
 
 <sect1info>
 <author>
 <firstname>Aaron</firstname>
 <surname>Price</surname>
 <affiliation><address>
 <email>aavso@aavso.org</email>
 </address></affiliation>
 </author>
 </sect1info>
 
 <title>AAVSO Light Curves</title>
 <indexterm><primary>Tools</primary>
 <secondary>AAVSO Lightcurve Generator</secondary>
 </indexterm>
 
 <screenshot>
 <screeninfo>
 The AAVSO Lightcurves Tool
 </screeninfo>
 <mediaobject>
   <imageobject>
     <imagedata fileref="aavso.png" format="PNG"/>
   </imageobject>
   <textobject>
     <phrase>AAVSO Lightcurves</phrase>
   </textobject>
 </mediaobject>
 </screenshot>
 
 <sect2 id="aavso-intro">
 <title>Introduction</title>
 <para>
 &kstars; can display light curves for variable stars from the observing
 program of the <ulink url="https://www.aavso.org">American Association
 of Variable Star Observers</ulink> (<abbrev>AAVSO</abbrev>).  This
 program monitors over 6,000 variable stars and consists of 10 million
 observations going back almost a century.  &kstars; downloads the very
 latest data directly from the <abbrev>AAVSO</abbrev> database via the
 Internet, so a network connection is required to use this tool.
 </para>
 <para>
 To use the tool, select a variable star either by
 <firstterm>designation</firstterm> or name in the left panel, and
 set the start and end dates to be plotted.  In the right panel,
 select the type of data that should be plotted (see below).  When you have
 made you selections, press the <guibutton>Retrieve Curve</guibutton>
 button.  &kstars; will automatically connect to the AAVSO server,
 which will generate the lightcurve plot and send it to your computer for
 display.  A sample lightcurve plot is shown below:
 </para>
 
 <screenshot>
 <screeninfo>
 A Sample Lightcurve
 </screeninfo>
 <mediaobject>
   <imageobject>
     <imagedata fileref="lightcurve.png" format="PNG"/>
   </imageobject>
   <textobject>
     <phrase>Sample Lightcurve</phrase>
   </textobject>
 </mediaobject>
 </screenshot>
 
 <para>
 Please not these light curves should <emphasis>NEVER</emphasis> be used
 in research, papers, presentations, publications, &etc; They are only
 meant to be used as a source of info for &kstars;. They have not been
 validated and passed the <abbrev>AAVSO</abbrev>'s strict quality control
 measures. We will be glad to give you good raw data simply by requesting
 it at <ulink url="http://www.aavso.org/adata/onlinedata/">http://www.aavso.org/adata/onlinedata/</ulink>.
 </para>
 <!-- broken link in 4.7 -->
 <para>
 Specific questions about the data in the light curves can be sent to
 <email>aavso@aavso.org</email>.
 </para>
 </sect2>
 
 <sect2 id="aavso-about">
 <title>About Variable Stars</title>
 <para>
 <firstterm>Variable stars</firstterm> are stars that change in
 brightness.  A <firstterm>light curve</firstterm> is a plot of a
 variable star's brightness over time. By looking at a light curve you
 can see how the star has behaved in the past and try to predict how it
 will behave in the future. Astronomers also use this data to model
 astrophysical processes in the star. This important to help us
 understand how stars work.
 </para>
 </sect2>
 
 <sect2 id="aavso-data">
 <title>The Data</title>
 
 <para>
 Here is a summary of the various types of data available in the light
 curves:
 
 <itemizedlist>
 <listitem><para><firstterm>Visual Observation</firstterm>:
 This is an observation of a variable star by an observer with a
 regular telescope.  It means that an observer saw the star at Y
 brightness on X date and time.</para></listitem>
 
 <listitem><para><firstterm>Fainter than</firstterm>:
 Sometimes the star is too faint to be seen by the observer. When that
 happens, the observer reports the faintest star seen in the field.
 These are called <quote>fainter thans</quote> because the variable star
 was fainter than the brightness reported.</para></listitem>
 
 <listitem><para><firstterm>Average</firstterm>:
 This is a computed running average of all the data reported. The
 <firstterm>bin</firstterm> number tells the computer how many days to
 use in each average calculation. This will need to be adjusted based on
 the frequency of observations. The error bars represent the 1 sigma
 standard deviation of error.</para></listitem>
 
 <listitem><para><firstterm>CCDV</firstterm>:
 These are observations reported using a <abbrev>CCD</abbrev> with a
 Johnson <abbrev>V</abbrev> filter.  <abbrev>CCDV</abbrev> observations
 tend to be more accurate than visual (but not
 always).</para></listitem>
 
 <listitem><para><firstterm>CCDB</firstterm>:
 <abbrev>CCD</abbrev> observations with a Johnson <abbrev>B</abbrev>
 filter.</para></listitem>
 
 <listitem><para><firstterm>CCDI</firstterm>:
 <abbrev>CCD</abbrev> observations with a Cousins <abbrev>Ic</abbrev>
 filter.</para></listitem>
 
 <listitem><para><firstterm>CCDR</firstterm>:
 <abbrev>CCD</abbrev> observations with a Cousins <abbrev>R</abbrev>
 filter.</para></listitem>
 
 <listitem><para><firstterm>Discrepant Data</firstterm>:
 This is data that has been flagged by an <abbrev>AAVSO</abbrev> staff
 member as being discrepant following <abbrev>HQ</abbrev> rules for
 data validation. Contact <email>aavso@aavso.org</email> for more
 information.</para></listitem>
 
 <listitem><para><firstterm>Dates</firstterm>:
 The observational database the light curves are based on is updated
 every 10 minutes so you can get data in near real-time. Right now
 light curve data is only available back to 1961, but this will likely
 be expanded further back in time in the future.</para></listitem>
 
 </itemizedlist>
 </para>
 </sect2>
 
 <sect2 id="aavso-update">
 <title>Updating your local copy of Variable Stars</title>
 <para>
 The <abbrev>AAVSO</abbrev> publishes the <!-- broken link in 4.7 -->
 <ulink url="http://www.aavso.org/valnam.txt">full list of variable
 stars</ulink> in their monitoring program.  This file is updated
 monthly with newly discovered variable stars.  To sync the list that
 &kstars; uses with the <abbrev>AAVSO</abbrev> master list, click
 on the <guibutton>Update List</guibutton> button in the
 <abbrev>AAVSO</abbrev> dialog.  &kstars; will then attempt to
 connect to the <abbrev>AAVSO</abbrev> database and download the
 latest list.
 </para>
 <note>
 <para>
 The customized data stream provided by the AAVSO was implemented for
 &kstars; by Aaron Price.  Thank you, Aaron!
 </para>
 </note>
 </sect2>
 </sect1>