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A description is given of a radar facility operating in New Zealand which measures the atmospheric trajectories and hence heliocentric orbits of earth-impacting meteoroids having radiants with declinations +5° < δ < −30° down to a limiting radar meteor magnitude of +13 (corresponding to particle sizes of ~100 μm, masses ~10−6 g). The data handling capacity of the facility permits recording, orbit reduction and efficient presentation of orbital data using graphical packages to be carried out on a routine basis. The daily yield is ~1500 individual orbits with >3×105 secured to date; this is greater than the number determined in all previous meteoroid orbit surveys combined and forms a major southern hemisphere database for dynamical studies of the solar system meteoroid population.
The mechanisms by which agriculture spread across Europe in the Neolithic, and the speed at which it happened, have long been debated. Attempts to quantify the process by constructing spatio-temporal models have given a diversity of results. In this paper, a new approach to the problem of modelling is advanced. Data from over 300 Neolithic sites from Asia Minor and Europe are used to produce a global picture of the emergence of farming across Europe which also allows for variable local conditions. Particular attention is paid to coastal enhancement: the more rapid advance of the Neolithic along coasts and rivers, as compared with inland or terrestrial domains. The key outcome of this model is hence to confirm the importance of waterways and coastal mobilities in the spread of farming in the early Neolithic, and to establish the extent to which this importance varied regionally.
A wavelet enhancement based method developed by Galligan and Baggaley to search for showers in radar meteoroid orbit data sets has been systematically applied to data obtained from the AMOR radar facility. This class of technique, applied for the first time here, has proved to be powerful. Less than 1% of this data set are found to be within recognisable shower groupings—generally only the major Southern Hemisphere meteor showers (η Aquarids, Southern δ Aquarids, α Capricornids and Daytime Sextantids) are detectable. Further probing with wavelets to select shower members, once the existence of the latter has been established, is found to be convenient. The orbital characteristics of the shower meteors thus selected are explored where it is found that the orbital parameter spreads in most showers do not exceed those expected due to measurement uncertainty.
Because the division consists of many very active commissions, most activities are included in the reports of the individual commissions. This report highlights a small subset of the major achievements that are covered in detail in the reports by the commissions. Some administrative activities of the division and reports of the divisional working groups and committees are also included as subsequent sections of this divisional report.
The IAU Meteor Data Centre (MDC), maintained at Lund, Sweden, under the direction of Bertil Lindblad, remains a valuable resource for the meteor community. Commission 22 currently has representatives on two inter-commission Working Groups, The Prevention of Interplanetary Pollution (Chair C. S. L. Keay of Commission 22) and Near-Earth Objects (IAU C22 representative I.P. Williams). The Commission has one Working Group of its own, Amateur-Professional Co-operation in Meteors, consisting of P. Jenniskens (Chair), H. Betlem, N. Bone, P. Brown, T. Cooper, I. Hasegawa, R. Hawkes, G. Klar-Renner, V. Porubčan, J. Rendtel, J. Richardson, T. Yoshida. Meetings of the working group were held in Japan in Aug 1997 and in Ithaca, NY in Jul 1999, and circulated periodic electronic newsletters. The working group helped establish professional-amateur collaborations during the Leonid campaigns of November 1998 and 1999, facilitated amateur participation in NASA’s Leonid Multi-Instrument Aircraft Campaign, and encouraged publication of amateur observations. The IAU Commission 22 www site has the following new location: http://www.mta.ca/rhawkes/IAU22.
As before a number of authors have contributed reviews of their own field. The contributions were editted by the President in order to avoid some overlaps, to reduce the length of the reviews and to add some publications. Reference numbers from “Astronomy and Astrophysics Abstracts” were used when available. In the end of the report a list of references not found in “Abstracts” is given. As editor, the President takes the responsibility for any shortcomings in the report.
Following past practice, a number of authors have contributed reviews of their own field. The contributions have been edited by the President in order to avoid some overlaps, to reduce the length of the reviews an to add some publications. When possible reference numbers in the Astronomy and Astrophysics Abstracts are used. As editor, the President accepts responsibility for any shortcamings in the report.
Meteoroid ablation in an atmosphere produces a weak plasma column. The processes important in governing the state of the meteoric species subsequent to column formation are reviewed. The actions of transport and of chemical reactions in controlling the life of the various species in the column are described. It is found that the interaction of meteoric ions with atmospheric gases leads to the dissipation of ionization and is the source of anomalous radio-meteor echo characteristics: recognition of these effects is important in permitting meaningful interpretations of radio-meteor data. Several modes of interaction between meteoric species and an atmosphere can yield enduring emissions. The fate of the various species is discussed.
A problem commonly encountered in meteor studies is the need for a realistic interpretation of statistical data which contains uncertainties in two variables. A simple solution is provided and for illustration applied to diffusion-height data.