VStar

What is VStar?

VStar is a multi-platform, easy-to-use variable star data visualization and analysis tool that was developed as part of the Citizen Sky [1] project. Data for a star can be read from the AAVSO database or from a text file of your own creation. It will plot the data on a light curve then its up to you what happens next!

Launching VStar

To get started using VStar, simply click here to get the latest version:

Version 2.15.2 Change Log
[3]

Because VStar uses Java Web Start ™ technology, you will always get the latest version whether you save the start-up icon to your desktop or launch the program directly. You will see a warning dialog box, similar to those presented by other Web-downloaded applications. Click the "Trust" button, in order to launch VStar. Please note that in order to run VStar, you need to have the Java Runtime Environment 1.6 [4] or higher installed.  VStar should run on any operating system that supports Java.

If you have a firewall which blocks connection to the AAVSO server (for access to the AAVSO database) you should either disable or run VStar offline. To do this, visit the SourceForge VStar download page [5] and download the latest VStar-(version).zip file, unzip it and place it in the location of your choice on your computer. The ReadMe.txt file contains instructions for running VStar from there.

NOTE: Mac users with OS X 10.7 or higher, may not be able to use Java Web Start applications. If this is the case, follow the instructions above for running VStar from your local system.

Using VStar

The easiest way to obtain data to plot is by requesting it directly from the AAVSO International Database. To do this, click the “New Star from AAVSO Database…” button in the upper left corner of the VStar screen, then choose a star from the 10-star [6] drop-down list or type in the name of another star from the AAVSO database. You can change the date range of the plot, use the default range (the last two years worth of data), or select “All data” by clicking the checkbox and hitting “OK”. Other features include the ability to create your own list of favorite stars to view using the "Star Groups" tab under "Preferences" or to filter the data so you can highlight your own observations.

What Next?

The 5-Star Data Analysis Tutorial [7] is available for download from the Citizen Sky web site.  This document will introduce you to VStar as well as a few other tools on the Citizen Sky site. The tutorial will also introduce you to some of the concepts of basic data analysis. We recommend it as the first place to stop for those new to light curves and variable star data analysis. More help links can be found below.

Some of the things you can do with VStar include:

Mean Curve plot mean curve with or without error bars change bin size display graphically or in tabular form save or print results
Phase Plot gets default period and epoch from VSX or set your own choose band to phase get means of plot display graphically or in tabular form save or print results
Period Analysis use Date Compensated Discrete Fourier Transform (DC DFT) run CLEANest period analysis refinement algorithm perform Weighted Wavelet Z-Transform (WWZ) for time-frequency analysis create new phase plots based on selections change parameters used view results several different ways
Polynomial Fit select series to fit select degree of polynomial show residuals if desired
Plug-ins create your own or choose one from the VStar Plug-in Library [8] some examples include plug-ins to: import Kepler or SuperWASP FITS files compute calendar date from JD filter observations per your specifications

Help!

There is limited help available in the VStar “Help” menu which you can see in the menu bar along the top of the screen. More help and tutorials are in work. In the mean time, here are some resources you might find useful:

• AAVSO VStar forum [9] - Please feel free to post your questions, suggestions, or observations here.
• AAVSO Data Analysis forum [10] - For discussion of data analysis techniques and projects.
• David Benn's VStar blog [11] - Contains good examples of how VStar can be used for data analysis.
• eJAAVSO article: Algorithms + Observations = VStar [12] - Outline of the development, use and future plans.
• Citizen Sky VStar software development forum [13]
• Powerpoint Presentation on VStar (English) [14]
• Powerpoint Presentation on VStar (Spanish) [15]

Other Information

• VStar is the creation of lead developer David Benn with help from the VStar Team [13].
• VStar uses the Apache Commons Math library for anova (F-test, p-value) algorithms.
• VStar is made available under the Affero GNU Public License [16], which requires that the source code be made freely available. Click here to visit its Sourceforge [17] site.

In addition, you can obtain information about libraries used by VStar here:
jcommon-1.0.16.jar (http://www.jfree.org/jcommon/ [18])
jfreechart-1.0.13.jar (http://www.jfree.org/jfreechart/ [19])
mysql-connector-java-5.1.10-bin.jar (http://dev.mysql.com/downloads/connector/j/5.1.html [20])