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Results are presented from a video-based meteoroid orbit survey conducted in New Zealand between Sept. 2014 and Dec. 2016, which netted 24,906 orbits from +5 to −5 magnitude meteors. 44 new southern hemisphere meteor showers are identified after combining this data with that of other video-based networks. Results are compared to showers reported from recent radar-based surveys. We find that video cameras and radar often see different showers and sometimes measure different semi-major axis distributions for the same meteoroid stream. For identifying showers in sparse daily orbit data, a shower look-up table of radiant position and speed as a function of time was created. This can replace the commonly used method of identifying showers from a set of mean orbital elements by using a discriminant criterion, which does not fully describe the distribution of meteor shower radiants over time. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, meteor outbursts and storms have greatly increased the likelihood of detection for meteor spectrographs with a small field of view. The successful prediction of the Leonid storms has made the deployment of new spectrographic techniques possible. Here, we apply a prediction model developed for the Leonid storms to the evolution of dust ejected from comet C/1854 L1 (Klinkerfues) in an effort to determine whether the 1981 outburst of ε-Eridanids may have been caused by this comet, and if so to predict future returns. We also investigated the possible link to comet C/962 B2. We find that the 1981 outburst may be explained as a Filament component (10–100 year old dust trails) from comet C/1854 L1, if that comet has an orbital period P ∼127 years. [Copyright &y& Elsevier]

Abstract: During the 2002 Leonid Multi-Instrument Aircraft Campaign, spectra were obtained of two Leonid meteors in the near-IR wavelength range of an InGaAs camera (0.96–1.46 micron). The spectrum contains atomic oxygen and nitrogen lines that are well-described by a typical warm 4400K meteoric plasma emitting in local thermodynamic equilibrium, but the First Positive Δν =0 band of N2 is weaker than expected. A quite bright continuum is also present, with a blackbody temperature of ∼4400K, much higher than that expected from hot debris. The cause of the continuum blackbody emission is a puzzle, as are several unidentified features. [Copyright &y& Elsevier]

A bright, estimated magnitude -3, Leonid meteor was observed from the University of Alaska Fairbanks Poker Flat Research Range north of Fairbanks, Alaska, at 10:42 UT on 18 November 2001. Images of the meteor were recorded at 1000 frames per second. The millisecond time resolution allows spatial structures in the ablation cloud to be recorded without “smearing” due to the ∼72 km/s Leonid entry velocity. The meteor was first observed at an altitude of about 123 km. As it descended deeper into the atmosphere it brightened and a tail developed. In addition, a bright structure developed in front of the meteor, much resembling a shock, reaching its maximum brightness at an altitude of 104 km. The spatial scale-size of the shock-like structure is large, several 100 m. Observation of such structure has, to our knowledge, not been reported before. We do not have an explanation for its cause. If its formation is similar to the shock observed around re-entry vehicles it would indicate the size of the meteor to be ∼100 m, which is clearly not realistic. The meteor will create ionization, but at 105 km the ion mean-free path is only ∼1 m and it is difficult to see how ionospheric plasma instabilities driven by the ionization caused by the meteor can result in ∼100 m structures. It is more likely that the structure is associated with photo-chemical processes driven by the intense UV radiation from the hot meteor. A simple computer simulation appears to be able to reproduce the observations. However, the process cannot just be photo ionization of the ambient molecular oxygen or nitrogen as the required total photon flux is too large to be energetically possible. [Copyright &y& Elsevier]