You need to find the IAU of your constellation:
You need to find exoplanets inside the cordinates of our constellation, we can find in this website. In my case I picked the HD 52265 b.
To get the linear regression graphic of your exoplanet, you need to use this website. This is the graphic from HD 52265 b.
Now, with the data from the graphic, we realize the formula: The R is 0,14