Die ESA hat bestätigt, daß es sich um eine Soyus-Oberstufe handelte:
Dear friends of #ESA, the special timing was rather a coincidence... but this mysterious trail was seen on 24 December evening over the skies of central Germany and parts of N-France, Belgium, N-CH, etc. To be clear: It was a used #Soyuz upper stage that burnt up in the high atmosphere. On 21 Dec., the launcher had successfully brought our André #Kuipers into orbit...! 
Gruss
Jens
