STAR: ABenchmark for Astronomical Star Fields Super-Resolution Appendix

Computing image plane coordinates: For a given high-resolution (HR) image with the resolution of H W and a downsampling rate s, we generate the size of the downsampled low-resolution (LR) image, referred to as Hs Ws . With the two sizes, we have specific coordinates of pixels in both LR and HR images. Transfer pixels to sky: For HR and IR pixel coordinates, we transfer them into the celestial coordinate system as: (u,v) (ra,dec), where (u,v) is a coordinate in the image plane while (ra,dec) is the longitude and latitude coordinates of the Earth. Note that, each pixel is not an ideal point and actually a rectangle on the image plane. After the mapping, it becomes a quadrilateral surface of the celestial coordinate system.