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