Deepest ever photographed Geminid with small but non-negligible terminal mass

We report an instrumental observation of the very exceptional Geminid fireball that was observed in the scope of the Czech part of the European Fireball Network (EN) on 13 December, 2012 at 4 h 12 m 59.4 s UT. The uniqueness of this Geminid fireball consists of the record depth of its penetration in the atmosphere (to the height of 32.5 km) and in the fact that a very small fraction of its initial mass most likely survived severe deceleration in the atmosphere and landed on the ground. Such a deeply penetrating Geminid with such precise and reliable data had not yet been observed. From a comparison with a large number of Geminids observed by the EN and all the brightest Geminids from the Prairie Fireball Network in the USA (PN) and Canadian MORP Network (MORP), we show that for Geminids with an entry mass greater than approximately 10 grams, the terminal altitude limit does not decrease further –as it does for smaller Geminids– but remains constant at around 38 km. In this comparison, we show that there is only one exception and that is the Geminid presented here. This one penetrated nearly 6 km deeper, with a very low terminal speed for a Geminid. During the atmospheric flight, this Geminid meteoroid slowed down from its original speed of 35.75 to 6.8 km s −1 . This small meteoroid with an initial mass of only 0.25 kg is probably the fastest candidate for a meteorite dropping event ever observed. This solid meteoroid belonging to the meteor shower survived a significant dynamic pressure of almost 2 MPa and thus ranks among the interplanetary bodies of asteroidal origin that caused the observed meteorite fall. Although a similar Geminid event has previously been presented in the literature, we demonstrate that this claim was flawed.