INTRODUCING AVE by Rafael Barberá english version by Jordi Iparraguirre Versión en Castellano
In 1995, GEA (Grup d'Estudis Astronomics) started a program to study the NSV (New Suspected Variable) stars catalogued. It is being a huge project but very rewarding too. Since Feb 95 to Dec. 98 (almost 3 years) the GEA team has studied more than 500 variable stars, classifying for the first time ever lots of them and discovering about 100 new variable stars.
All GEAs results have been published in the IBVS. As you can imagine, all that means loooots of photometric data to process and analyze. It was clear that we needed a tool, so I started AVE to fit the GEA needs.AVE, Analisis de Variabilidad Estelar, stands for Analysis of Estellar Variability.
The requirements to develop AVE where pretty simple:
WORKING WITH AVE
AVE reads plain ASCII files that contain the Julian dates and the differential magnitude. If you use LAIA, you do not need to worry about the file and its format as LAIA does it all for you. A data file could look like this:
2450339.4750136 -0.098 2450339.4800717 -0.102 2450339.4842684 -0.101 2450339.4877663 -0.098 2450339.4913430 -0.104 2450339.4945300 -0.091 2450339.4982626 -0.103 2450339.5014504 -0.097 2450339.5058791 -0.098
If we open one of those data files with AVE,
our screen will show something like:
Nice isn't it ? Now let's have a look to some interesting details. First of all, if you want to have a full resolution graphic (800 x 600) just click twice on it.
But AVE is much more than a light-curve-displaying-tool.
To prove it, let's select the option called Tools/Period Searching and we will see
(after clicking on the desired option in the context menu) a dialog box like the following
The dialog box is asking us for an interval of periodes where to look for, number of samples inside the interval and to select an algorithm (as there are different algorithms to find a periode in a cloud of points). The AVE sets a merit function (depends on the algorithm selected) for each sample. Then, by simply having a look to the Periode/Merit function graphic, you can determine the possible periodes of the data.
In the example, we have selected the PDM algorithm, (also known as Theta
transformation). In that case, the Merit curve represents how clustered are the points
respect the the average curve. That implies that the lowest the value of the function, the
highest probabilitys is that the periode produced on this mimimum is significative.
Whoou !! Difficult ? Do not worry, it is easy now. Right mouse button to
select a minimum, and Right mouse button again to generate a phase curve in that periode
...Voila ! A nice eclipsing light curve.
What we need now is to determine several minima and the exact moment of each one of them. Is AVE able to all that automatically for us ? Of course it is !
First set a threshold clicking with the right button of the mouse on the
curve (having the minima-detection tool activaded). Then select the Find All option
and after few moments all the minima will be indicated on the curve with a blue arrow. Now
we just need to create a file with all this information (minima epoch and its error).
Minima are identified using the Van Woerden method and it can be configured to adapt to your curves (i.e. in case of having a few dots). OTHER OPTIONS
Among the options not explained above, AVE is able to:
Even if there is no help file, nor a manual, the best way to appreciate the power and features of AVE is downloading it !. If you have questions about AVE do not hesitate to get in touch with me by email. FUTURE
There are not going to be new 16 bit versions of AVE. The tool is being moved to 32 bits to take more advantadge of the new generation of Windows operating systems. Future features will only be implemented on the 32 bits version. Some of those features are:
New releases will be announced and available for download in this page. There is also a mail list of AVE users that will allow you to talk with the developer and to exchage experiences with other users. Send your coments to firstname.lastname@example.org
References [ Personal Page ][ GEA ]
Last modification: Dec. 1996