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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="http://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>
<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
<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>
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