1 <sect1 id="tool-aavso">
5 <firstname>Aaron</firstname>
6 <surname>Price</surname>
8 <email>aavso@aavso.org</email>
9 </address></affiliation>
13 <title>AAVSO Light Curves</title>
14 <indexterm><primary>Tools</primary>
15 <secondary>AAVSO Lightcurve Generator</secondary>
20 The AAVSO Lightcurves Tool
24 <imagedata fileref="aavso.png" format="PNG"/>
27 <phrase>AAVSO Lightcurves</phrase>
32 <sect2 id="aavso-intro">
33 <title>Introduction</title>
35 &kstars; can display light curves for variable stars from the observing
36 program of the <ulink url="http://www.aavso.org">American Association
37 of Variable Star Observers</ulink> (<abbrev>AAVSO</abbrev>). This
38 program monitors over 6,000 variable stars and consists of 10 million
39 observations going back almost a century. &kstars; downloads the very
40 latest data directly from the <abbrev>AAVSO</abbrev> database via the
41 Internet, so a network connection is required to use this tool.
44 To use the tool, select a variable star either by
45 <firstterm>designation</firstterm> or name in the left panel, and
46 set the start and end dates to be plotted. In the right panel,
47 select the type of data that should be plotted (see below). When you have
48 made you selections, press the <guibutton>Retrieve Curve</guibutton>
49 button. &kstars; will automatically connect to the AAVSO server,
50 which will generate the lightcurve plot and send it to your computer for
51 display. A sample lightcurve plot is shown below:
60 <imagedata fileref="lightcurve.png" format="PNG"/>
63 <phrase>Sample Lightcurve</phrase>
69 Please not these light curves should <emphasis>NEVER</emphasis> be used
70 in research, papers, presentations, publications, &etc;. They are only
71 meant to be used as a source of info for &kstars;. They have not been
72 validated and passed the <abbrev>AAVSO</abbrev>'s strict quality control
73 measures. We will be glad to give you good raw data simply by requesting
74 it at <ulink url="http://www.aavso.org/adata/onlinedata/">http://www.aavso.org/adata/onlinedata/</ulink>.
77 Specific questions about the data in the light curves can be sent to
78 <email>aavso@aavso.org</email>.
82 <sect2 id="aavso-about">
83 <title>About Variable Stars</title>
85 <firstterm>Variable stars</firstterm> are stars that change in
86 brightness. A <firstterm>light curve</firstterm> is a plot of a
87 variable star's brightness over time. By looking at a light curve you
88 can see how the star has behaved in the past and try to predict how it
89 will behave in the future. Astronomers also use this data to model
90 astrophysical processes in the star. This important to help us
91 understand how stars work.
95 <sect2 id="aavso-data">
96 <title>The Data</title>
99 Here is a summary of the various types of data available in the light
103 <listitem><para><firstterm>Visual Observation</firstterm>:
104 This is an observation of a variable star by an observer with a
105 regular telescope. It means that an observer saw the star at Y
106 brightness on X date and time.</para></listitem>
108 <listitem><para><firstterm>Fainter than</firstterm>:
109 Sometimes the star is too faint to be seen by the observer. When that
110 happens, the observer reports the faintest star seen in the field.
111 These are called <quote>fainter thans</quote> because the variable star
112 was fainter than the brightness reported.</para></listitem>
114 <listitem><para><firstterm>Average</firstterm>:
115 This is a computed running average of all the data reported. The
116 <firstterm>bin</firstterm> number tells the computer how many days to
117 use in each average calculation. This will need to be adjusted based on
118 the frequency of observations. The error bars represent the 1 sigma
119 standard deviation of error.</para></listitem>
121 <listitem><para><firstterm>CCDV</firstterm>:
122 These are observations reported using a <abbrev>CCD</abbrev> with a
123 Johnson <abbrev>V</abbrev> filter. <abbrev>CCDV</abbrev> observations
124 tend to be more accurate than visual (but not
125 always).</para></listitem>
127 <listitem><para><firstterm>CCDB</firstterm>:
128 <abbrev>CCD</abbrev> observations with a Johnson <abbrev>B</abbrev>
129 filter.</para></listitem>
131 <listitem><para><firstterm>CCDI</firstterm>:
132 <abbrev>CCD</abbrev> observations with a Cousins <abbrev>Ic</abbrev>
133 filter.</para></listitem>
135 <listitem><para><firstterm>CCDR</firstterm>:
136 <abbrev>CCD</abbrev> observations with a Cousins <abbrev>R</abbrev>
137 filter.</para></listitem>
139 <listitem><para><firstterm>Discrepant Data</firstterm>:
140 This is data that has been flagged by an <abbrev>AAVSO</abbrev> staff
141 member as being discrepant following <abbrev>HQ</abbrev> rules for
142 data validation. Contact <email>aavso@aavso.org</email> for more
143 information.</para></listitem>
145 <listitem><para><firstterm>Dates</firstterm>:
146 The observational database the light curves are based on is updated
147 every 10 minutes so you can get data in near real-time. Right now
148 light curve data is only available back to 1961, but this will likely
149 be expanded further back in time in the future.</para></listitem>
155 <sect2 id="aavso-update">
156 <title>Updating your local copy of Variable Stars</title>
158 The <abbrev>AAVSO</abbrev> publishes the
159 <ulink url="http://www.aavso.org/valnam.txt">full list of variable
160 stars</ulink> in their monitoring program. This file is updated
161 monthly with newly discovered variable stars. To sync the list that
162 &kstars; uses with the <abbrev>AAVSO</abbrev> master list, click
163 on the <guibutton>Update List</guibutton> button in the
164 <abbrev>AAVSO</abbrev> dialog. &kstars; will then attempt to
165 connect to the <abbrev>AAVSO</abbrev> database and download the
170 The customized data stream provided by the AAVSO was implemented for
171 &kstars; by Aaron Price. Thank you, Aaron!