The $10,000 Sextant Challenge

"A sextant can only work on a flat Earth" - the claim that celestial navigation is proof of the flat model.

Use two different sets of elevation angles to three separate stars to determine the observer's location using only flat-earth geometry. First set: Regulus 70°48.7', Arcturus 27°9.0', Dubhe 55°18.4' (observed 15 Nov 2018). If the first is solved, a second set is published and the exact same method must work on it too.

Within 25 statute miles for both sets (latitude/longitude, address, or distance+bearing to a landmark). The full method must be published and independently reproducible by a third party. No globe-derived maps, star charts, dip charts, refraction tables, or surface-distance calculations. Every numerical constant must be derived or cited. Only known, documented light propagation. Official file carries a published SHA-256 checksum; parameters cannot be modified after publication (Legit Challenge Framework v0.9b).

$10,000 in Bitcoin, in escrow since 2022. Status on MCToon's site: 'Submissions: none yet.'

The claim that a sextant 'only works on a flat Earth' implies that two centuries of celestial navigation never worked - the challenge asks for the method, not the belief. The relaxed version (the Global Navigation Challenge, which allows the celestial sphere) was solved in 4 minutes; the strict flat-geometry version has had zero submissions for over four years.