Japanese version Home Page Updated on January 22, 2006
How to Discover Variable Star
This page introduces how to discover a new variable star from two images taken with a proper interval time using the PIXY System 2.
Here are the two sample FITS images used in this page. Please download them.
These two images cover the same field, taken with an interval of 47 days using a 18-cm reflector. Now let's compare the two images and search a new variable star using the PIXY System 2.
Here are the steps to search a new variable star using the PIXY System 2.
Let's follow the steps in detail.
First of all, run the PIXY System 2 and select the [Tool] - [Image Collation] menu in the main menu window. (*)
Then a new virtual desktop appears.
First, open the two images to compare. Select the [Operations] - [Open Image] menu and open one of the sample images you downloaded. After the first image appears, select the [Operations] - [Open Image] menu again and open the other image.
Then select the [Operations] - [Matching] menu and wait for some seconds, while the PIXY System 2 is matching the two images to overlap precisely.
Finally, search comets or asteroids by the R-GB method. The R-GB method is a way to search variable or moving stars designed by KenIchi Kadota. Two images are composed, one represents red color and the other represents blue and green color, and a color image is created. Whole of the new image becomes monochrome, however only variable or moving stars become red or greeny blue.
Select the [Operations] - [Create R-GB Image] menu and create the R-GB image. When the R-GB image appears, click right button of your mouse on the image and you can adjust the brightness, zoom up, and so on.
In case of the sample image, there are a red star and a blue star at the image center. In addition, looking over the whole image, I found two slightly blue stars, bluer than neighbor stars, above of the image center and the bottom left corner.
These four stars are supposed to be variable.
I examined the two sample images following the steps described in the Examine Your Image page. As a result, the R.A. and Decl. and the magnitude of these four stars are obtained as follows.
Investigating the variable star catalogs, the star 1 is a known variable star V4334 Sgr. However, star 2, 3, and 4 are not recorded as variable stars. Actually, these three stars are new. The MISAO Project announced them as MISAO Project variable stars, MisV0001, MisV0786 and MisV1009.