ground-based telescope with a diameter of 20r0. See en:Seeing_disk, Image:ast_seeing_2r0.png and Image:ast_seeing_7r0.png. English determination method: SHA-1
ground-based telescope with a diameter of 2r0. See en:Seeing_disk, Image:ast_seeing_7r0.png and Image:ast_seeing_20r0.png. English determination method: SHA-1
ground-based telescope with a diameter of 7r0. See en:Seeing_disk, Image:ast_seeing_2r0.png and Image:ast_seeing_20r0.png. English determination method: SHA-1