Update README.md

README/EN/README.md

@@ -38,7 +38,7 @@ If you prefer to use the simulation offline, follow these instructions:
 
 The real-time simulation of Pulsar 3D utilizes the Three.js library for camera control, 3D object creation, and functions such as the SkyBox for background control and 3D immersion.
 
-The real stellar background from NASA, found in [Deep Star Maps](https://svs.gsfc.nasa.gov/4851/), provides an authentic and immersive environment for the simulation.
+The real stellar background from NASA, found in [Deep Star Maps](https://svs.gsfc.nasa.gov/4851/), provides an authentic and immersive environment for the simulation. This set of star maps was created by plotting the position, brightness, and color of 1.7 billion stars from the Hipparcos-2, Tycho-2, and Gaia Data Release 2 star catalogs.
 
 Furthermore, the simulation includes descriptive images of pulsar behavior, providing a valuable educational resource for classroom use. The simulation enables visualization and interaction with pulsar rotation, magnetic fields, and radiation emissions. Users can observe how these elements interact and affect the environment around the pulsar, providing a deeper understanding of these fascinating astronomical phenomena.