RENCHEN meteorite fall (~ 999.49 g, L5-6, S4, W0) on 10 July 2018 at 23:29:48 CEST (21:29:48 UTC) near Renchen, Ortenau district, Baden-Württemberg, Germany
The first find (Renchen-1, 11.9 g)
Equipped with a preliminary strewn field map provided by Pavel Spurný on July 14, 2018 and coordinated by Dieter Heinlein the meteorite hunters Ralph Sporn and Martin Neuhofer were sent to the calculated strewn field on 15 July and stayed there until 18 July, mainly to explore the area. Sporn and Neuhofer returned to the strewn field on 22 July and on 24 July around noon Ralph Sporn found Renchen-1 (11.9 g), an almost complete specimen, in a cherry orchard at location 48°34’26.4” N, 8°01’8.8 E, about 1.48 km southeast of Renchen.The second find (Renchen-2 (main mass), 955 g)
On 30 July around noon Pavel Spurný transferred another map of the part of the strewn field where larger masses were expected to have fallen to Sporn and Neuhofer who had returned to the strewn field for their third search campaign on 29 July. On 31 July Ralph Sporn and Martin Neuhofer found a large mass of 955 grams with a broken face next to a small shallow impact pit on a meadow near the Heuweg, east of Holchenbach in the south of the communal district Rheinau between the forests Korker Wald and Hürbewald about ~5.4 km north-west of Renchen. The locations of Renchen-1 and Renchen-2 were used by Dr Spurný to refine his strewn field calculation by 8 August 2018. Radio nuclides of the specimen have been measured at Max-Planck-Institut für Kernphysik (MPIK) in Heidelberg. The soil around and including the impact pit has been cut out and saved by the finders, similar to what has recently been done with the impact pits of the Stubenberg and Mangui falls.
At 11.40 a.m. on 1 September 2018 the team of Łukasz Smuła, Magdaleną Skirzewską and Thomas Kurtz found 19 fragments weighing between 8.62 and 0.18 grams of a meteorite fragment on a forest path in the Mührig state forest within the communal district of Renchen, Landkreis (district) Ortenau, Baden-Württemberg, Germany.
The meteorite, most likely one of the fragments which broke off the 955-gram mass Renchen-2, fragmented on impact on the gravel path and broke into at least 19 pieces and several sub-0.1-gram fragments. Four larger fragments were found along a more than 317-cm line crossing the path from southwest (~226°) to northeast. The distances between the find locations of the fragments are: R3B&C ← >132cm → R3TK1 ← ~82cm → R3A ← ~102.5cm → R3TK2). The three fragments R3B, R3C and R3TK2 were found in the grass next to the path and close to the respective crosses on the path.
Smuła and Skirzewską had been searching the area dedicatedly and intensively for more than a week when they teamed up with T. Kurtz on 1 September. The 8.62-gram fragment was found by Łukasz Smuła rather by accident while coming back from the dense undergrowth near a tree plantation southwest of the path where he had looked for meteorites in the high grass with a metal detector. The meteorite fragment stood out from the light-coloured compacted gravel of the forest path because of its fusion crusted surface area pointing upwards. Immediately after the team started looking for more fragments of the meteorite which most likely had shattered on impact on the compacted gravel of the forest path. Four larger meteorite fragments were found on and along the path. On 3 September another fragment was found at the edge of the path about three meters north-northwest from the fall location.
On 12 September two fragments of Smuła and Skirzewską’s meteorite (Renchen 3c and 3r5) weighing 1.298 and 0.054 grams were sent to Prof Dr Addi Bischoff and PhD student Markus Patzek at the Institut für Planetologie at the Westfälischen Wilhelms-Universität in Münster for classification. The classification result communicated by Dr Bischoff on 21 September indicate that Renchen (prov.) is an L-chondrite breccia (L5-6, S4, W0). On 24 December RENCHEN was officially registered in the Meteoritical Bulletin Database.The fourth find (Renchen-4, 4.8 g)
Just after noon on 30 September 2018, on their 26th day of searching, Sporn and Neuhofer found another meteorite weighing 4.8 grams at a height of 2.5 meters above the ground in a hail protection net above a raspberry plantation, east of Renchen.The fifth find (Renchen-5, 6.29 g)
At 1.08 p.m. on 13 October another intact specimen (18 x 16 x 13 mm) weighing 6.29 grams was found by Martin Kappler after 94 hours of systematic search and 18 trips to the strewn field.
The bolide’s luminous trajectory was recorded for about 4 seconds at ~23:29:48-52 CEST (21:29:48-52 UTC) on 10 July 2018. The bolide was recorded by several meteor cameras of the European Fireball Network (EN) in Germany and the digital automatic all-sky cameras (DAFO) in the Czech Republic. It was recorded on the digital DLR mirror camera in (78) Osenbach in Alsace, France (88.4 km from the fall location of Renchen-1) and the two German analog cameras in 87 Gernsbach (31.23 km from the fall location of Renchen-1) and 43 Öhringen (130.5 km from the fall location of Renchen-1). A digital camera at the Czech Hydrometeorological Institute in Přimda (361.1 km from the fall location of Renchen-1) and another in Churáňov (414.5 km from the fall location of Renchen-1) in the west of the Czech Republic equally captured the bolide very low above the horizon (10.4°-0.8°). Furthermore some private digital skycams in Karlsruhe-Knielingen (by Uwe Baron), Oberwolfach (by Martin Rebbe), at the observatory Welzheim (by Steffen Brückner) and in Schwarzenberg (by Rene Zinke) could capture it. In France a private digital camera in Chaligny (142.7 km from the fall location of Renchen-1) recorded the bolide’s luminous trajectory. Another capture is known from Schafmatt in Switzerland. The bolide was observed by several eye-witnesses in Germany, France, the Netherlands and Switzerland. The known data provided enough information to calculate the meteoroid’s pre-impact heliocentric orbit, its atmospheric trajectory, its dark flight trajectory and the potential fall area of meteorites.
The analysis of the luminous and dark flight trajectory was performed within one day by Dr Pavel Spurný and a team of the Interplanetary Matter Department at the Astronomical Institute of the Czech Academy of Sciences (CAS) in Ondřejov. The wind models were provided by Dr Gerd Baumgartner of the Leibniz-Institute of Atmospheric Physics in Kühlungsborn. According to P. Spurný’s calculation a meteoroid the size of a football was recorded entering the atmosphere with a speed of slightly below 20 km/s in a very steep angle of 80 degrees to the surface and started to radiate light at a height of 80 km above an area halfway between Waldulm (Kappelrodeck) and Ringelbach (Oberkirch). The bolide’s brightness increased rapidly and reached its maximum magnitude of –13.4 (recalculated value for a distance of 100 km). The luminous trajectory, containing one distinctive flare (after about 3 seconds) at a height of 28 km, lasted for about 4 seconds. It was about 63 km long and ended at a height of about 18 km above the ground slightly west of Renchen, Germany. The dark flight of a one-kilogram meteorite starting at the end point of the trajectory at a height of 18 km above the ground lasted for about 2 minutes. The smaller masses of about 1 to 10 grams resulting from the main flare at an altitude of 28 km took about 5 to 10 minutes to fall to the ground.
The strewn field of bolide EN100718 was determined to be in the Ortenau district near the small city of Renchen in western Baden-Württemberg, Germany. The calculated ~12.9 km²-strewn field consists of two distinctive areas: a broad area in the southeast where a few dozens of smaller masses of 1 to 50 grams resulting from the bolide’s main flare are expected to have fallen. Smaller specimens of about 10 grams are expected to have fallen above the city of Renchen and smaller masses of about one gram are expected to have fallen along a line stretching between the villages of Stadelhofen and Ulm. Larger fragments are expected to have fallen in the Mührig and Hürbewald forests within a small strip of the strewn field northwest of the motorway. In the morning of 2 October 2018 Dr Pavel Spurný published his press release / English version about this fall. A German version (PDF) of the press release written by Dieter Heinlein with a slightly different content can be downloaded here: German version (PDF). On 4 October Westfälischen Wilhelms-Universität Münster (WWU) published its press release.