The 2005 Draconid outburst

¹ University of Western Ontario, Department of Physics and Astronomy, London ON N6A 3K7, Canada e-mail: Margaret.Campbell@uwo.ca
² International Meteor Organization, PF 600118, 14401 Potsdam, Germany e-mail: rarlt@aip.de
³ Institut de Mécanique Céleste et de Calcul des Éphémérides, Observatoire de Paris, 77 avenue Denfert-Rochereau, 75014 Paris, France

Received: 24 November 2005
Accepted: 24 January 2006

Abstract

Aims.We report the flux profile and mean orbit for meteoroids associated with an unexpected activity outburst from the Draconid meteor shower on 8 October, 2005. The primary aim is to define the characteristics of the outburst and establish the age of the associated meteoroids.

Methods.Radar data from the outburst are used to define the flux profile and mass distribution for Draconid meteoroids at small meteoroid masses, while visual data are used to define the ZHR profile at larger masses. The radar recorded both single station and orbital data permitting orbits for many individual Draconid radar echoes as well as determination of a mean shower radiant.

Results.The peak activity was centered at 16.1 hrs UT, ( (J2000) solar longitude) with noticeably heightened radar activity lasting for a total of more than three hours. Based on the distribution of amplitudes for underdense Draconid echoes, the mean mass distribution index at masses of 10^-6 kg was found to be . The equivalent hourly-binned radar ZHR was in excess of 150, while visual observations in the same intervals produced ZHRs of 40. The apparent radiant of the outburst was , . Numerical modelling of radar–sized Draconids show that a significant number of meteoroids from the 1946 perihelion passage of 21P/Giacobini-Zinner encountered the Earth over the interval in 2005, centred about

Conclusions.The shower was rich in faint meteors, and therefore showed higher activity in radar data than in visual data alone. The duration of the outburst was very similar to past returns, while the mean radar stream orbit was somewhat different than previous measurements (the radiant differed by 6° in right ascension and 2° in declination) and also from the expected distribution of orbital elements for modelled 1946 meteoroids encountered in 2005.