An unexpected streak in a MASCOT image

Astronomers at ESO's frontline Paranal Observatory got a surprise on the morning of 18 December when looking at the observatory's fish-eye, all-sky camera, MASCOT. For about 45 minutes in the early morning, an object appeared first as a bright stripe then as a cloud that dissolved. It was quickly discovered that the same morning, about one hour before the object was seen from Paranal, the Japanese Aerospace Exploration Agency (JAXA) had launched a H-IIA rocket carrying the KIKU No. 8 (ETS-VIII) engineering test satellite, one of the largest geostationary satellites in the world.The object was most probably the 2nd stage of the launcher and the cloudy appearance at the end of the sequence most likely a dump of liquid fuel, made to avoid the explosion of the rocket in hundreds of scattered pieces, as a result of leftover fuel inside spent rocket stages.