International Asteroid Warning Network Timing Campaign : 2019 XS

Peer reviewe

A study of multilayer nanostructures [(Co

Interatomic interactions and superstructures of multilayer nanostructures (MLNS) consisting of ferromagnetic composite layers and silicon interlayers with or without hydrogen are studied here by means of X-ray diffraction (XRD), X-ray reflectivity (XRR), IR spectroscopy, and ultra-soft X-ray emission spectroscopy (USXES). The MLNS [(Co45Fe45Zr10)35(Al2O3)65/a-Si:H]100 and [(Co45Fe45Zr10)35(Al2O3)65/a-Si]120 were deposited on the substrate Si(100) by ion-beam sputtering of two targets, where the first target was a plate of Co45Fe45Zr10 alloy with Al2O3 inserts, and the second target was a single-crystal silicon. Our results show that the iron (FeSi2) and cobalt (CoSi, CoSi2) silicides are formed at the interfaces of the composite metal-containing layer/silicon interlayer. It is demonstrated that the metal clusters of composite layers and interface silicides are partially oxidized to form iron, cobalt, and silicon oxides together with zirconium silicate. Due to the formation of silicides at the interfaces, the composition of MLNS superstructures becomes more complex, and their periods are significantly reduced (down to 5–6 nm) compared to the nominal values of bilayers of about 6.9 nm

International Asteroid Warning Network Timing Campaign : 2019 XS

Peer reviewe

The Second International Asteroid Warning Network Timing Campaign: 2005 LW3

The Earth close approach of near-Earth asteroid 2005 LW3 on 2022 November 23 represented a good opportunity for a second observing campaign to test the timing accuracy of astrometric observation. With 82 participating stations, the International Asteroid Warning Network collected 1046 observations of 2005 LW3 around the time of the close approach. Compared to the previous timing campaign targeting 2019 XS, some individual observers were able to significantly improve the accuracy of their reported observation times. In particular, U.S. surveys achieved good timing performance. However, no broad, systematic improvement was achieved compared to the previous campaign, with an overall negative bias persisting among the different observers. The calibration of observing times and the mitigation of timing errors should be important future considerations for observers and orbit computers, respectively.Funder: Institute of Cosmos SciencesUniversity of Barcelona (CEX2019-000918-M); European Union (PID2021-122842OB-C21);Full text license: CC BY</p