Topex/Poseidon flaring

Monday evening was clear. I targetted the KH-12 Keyhole USA 129 - it is expected to manoeuvre one of these days.

While watching it (and photographing it), a bright mag. +0.5 flash occurred close to it, followed by another one and than a longer +1.5 flare. It turned out to be the malfunctioned US-French Oceanographic satellite Topex/Poseidon (92-052A), which I have observed flashing before. It malfunctioned in 2006 and since has started to tumble.

Below is the image showing both USA 129 and Topex/Poseidon, the latter showing the three flares:

click image to enlarge

The image yields this brightness curve, with peaks (two narrow and one broad) spaced 3.6 seconds apart:

click diagram to enlarge