In a Youtube video documenting an expariment done by youtuber MrThriveandSurvive. He observes a mirror flash of the sun through an inferared modified P-900 at a distence of 17.61 miles or 28.24km. See if you guys can help me debunk this. Video link: Source: https://www.youtube.com/watch?v=2_PHDgOS3ro Here are the atmospheric measurements that he took in order to calculate refraction using a snells law calculator. He also did a "three way mirror flash" in order to show that atmospheric refraction did not interfere with the results. the way that he explains it in the video is not extremely clear so I might have interpreterted it wrong but in essence, he has set up mirrors at all three points of the lake: A, B and C. he claims that in his experiment he flashes the mirror at point A and this flash can be obesrved at both point B and C. then the team at point C will flash the mirrors at both point B and A. The flashes are claimed to be seen again by the both teams and finially he flashes the mirrors at point B, the flash is seen by people at point A and C. He concludes that because of these three way triangular flashes, refraction could not have played a role in the observations as different densities in the air would not allow all three mirrors to be seen at all three points. This stage of the experiment was not documented in the video. A couple of issues with the expariment that I see already: 1. he does not explain the way he handles the mirrors while making the observations. we do not know if they were stationary set at a static angle or the teams were just wildly shaking them around until someone saw a reflection. 2. he did not account for the divergence of the reflected beam which means that we could be purely seeing the light on divergence, making the "3 way test irrelevant" 3. he failed to observe any moving vehicles or any of the team members on the infrared red camera, if the earth was indeed flat we should be able to see him and his team entirely, and be able to identify IR bloobs in the pictures of the mirror flashes.