Flaring Keyhole USA 129
It made a zenith-pass near 20:21 UTC during which it put on a spectacular show.
As it cleared the edge of the roof and came into my view in the zenith, it was very bright and clearly flaring. It must have been around mag. 0 to -1, peaking near or before 20:21:20 UTC. When my camera opened it was already past peak brightness for several seconds but still bright, gradualy fading. The image is below.
Obtained two positions from the image. My timings suggest it was 1.15s early with regard to elset 07066.85705303