The fireball over Lake Robozero
A report of 1663 to the St Cyril (Kirillo-Belozersky) monastery records that on 15 August, at midday, villagers gathered at the church of Robozero saw a great fire come down over the lake, give off rays, vanish and return, lighting the water to its depths.
1663 CE · 60.00, 37.90 · status: account
The account
The steward Ivashko Rzhevsky wrote down the testimony of the peasant Levka Fyodorov: the fire, about 40 metres across, had two fiery rays in front; peasants in a boat could not approach for the heat. The manuscript was found by the Archaeographic Commission in the 19th century and became a classic of 'historical UFO' collections (Vallée and Aubeck's 'Wonders in the Sky', 2009). The coordinates are approximate.
The sceptical view
Suggested explanations include ball lightning, a bolide or a mirage; the account is second-hand and written by a monastery official.