Of perhaps a satellite even brighter than the ISS? The
Iridium constellation features satellites with ~4x10' flat antenna panels that make wonderful mirrors. These antennae are held in predictable positions, making forecasts of flares very accurate.
I'd take a look at
what was predicted, but I'd need your exact lat/long coordinates as well as time. These things get brighter than the Moon's surface, but only over a very narrow strip of land, and for about 15 seconds or less.
HAVe fun,
Frank