Abstract Photon region (PR) in the strong gravitational field is defined as a compact region where photons can travel endlessly without going to infinity or disappearing at the event horizon. In Schwarzschild metric PR degenerates to the two-dimensional photon sphere $$r=3r_g/2$$ r=3rg/2 where closed circular photon orbits are located. The photon sphere as a three-dimensional hypersur... https://hollandscountryclothinges.shop/product-category/competition-shirts/