‘Comet-like’ rocket fuel dump observed from the British Isles

 Between 05:05 and 06:10 UTC on 2014 Dec 13 a comet-like object moving northwards through Serpens and into Corona Borealis was widely observed from many parts of the British Isles. Of particular note was the rapid change in brightness (rising from invisibility to first magnitude before fading to below naked-eye visibility) and the speed with which it moved across the sky, covering almost 20° in just over an hour.
Earlier that morning at 03:19 an Atlas V-541 rocket was launched from Vandenburg AFB in California. The payload was NROL-35,1 a classified US Signals Intelligence satellite which would be injected into a Molinya orbit by the hydrogen/oxygen fueled Centaur upper stage. In the days prior to the launch respected satellite observer and orbital analyst Ted Molczan used publicly available information to produce provisional orbital elements for the payload and booster, and posted them on the SeeSat L forum.
On the same forum Cees Bassa noted that during previous similar launches the Centaur performed a CCAM (Collision and Contamination Avoidance Manoeuvre), and that a propellant dump had been observed from the ground. If the mission managers followed a similar routine this time then this phenomenon would be visible from Europe. (continued….)

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