Comet for Windows Tutorial

Japanese version
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Updated on November 27, 2004


    Light Curve Analysis of chi Cyg    

o Introduction

Comet for Windows can import magnitude data, draw the graph, and analyze the light curves of variable stars.

Comet for Windows can import magnitude data in the following formats.

Please read the following web pages of the MISAO Project about the usage of The All Sky Automated Survey (ASAS) and Northern Sky Variability Survey (NSVS).

o Read magnitude data in VSNET format.

Here let's display light curve of a variable star chi Cyg.

First of all, please download the magnitude data from:

The magnitude data are recorded in VSNET format.

Please launch Comet for Windows and select "Menu" - "Light Curve of Variable Star" menu. Then select "Setting" - "Import Magnitude Data" - "VSNET Format" menu, and open the file you downloaded. Then the light curve is displayed as follows.

We can see the star is repeating brightening and fading.

o Display light curve of one period.

The star chi Cyg is known as a Mira type variable with a period of 408 days. So let's see the light curve of one period.

First, please select "Setting" - "Variable Star Information" menu, and "Variable Star Information" dialog appears. Please input "408" at "Period" part.

Next, please select "View" - "Format" menu, and "Format" dialog appears. Please select "Days from Epoch", and check "Fold and Overlay" check box.

Then the light curve is displayed as follows.

Almost all magnitude data are overlaid to form one curve. So we can confirm that the period of 408 days is correct.

We can also see that the star is repeating one pattern of linear fading for about 200 days and linear brightening for about 200 days.


Copyright(C) Seiichi Yoshida ( All rights reserved.