The 2011 Giacobinid outburst : meteoroid flux determination and orbital data by using video imagery from the Spanish fireball network

Abstract

On October 8th, 2011 the Earth encountered the dust trails left by comet 21P/Giacobini- Zinner during its XIX and XX century perihelion approaches. The encounter was forecasted in great detail [1, 2, 3]. Geometic circumstances were very favourable to produce a meteor storm, but unfortunately the trails were older than in previous 1933 and 1946 historical encounters. As a consequence of the decreased flux number density in the comet trails, during the 2011 Draconid night the Zenital Hourly Rate (ZHR) only just reached the outburst level with about 400 meteors/hour, and the display was strongly attenuated for visual observers due to the Moon observing circumstances [4]. Despite this, the possibility of recording usual meteor activity coming from a lowgeocentric velocity meteoroid stream motivated us to develop a special observing campaign. The encounter of our planet with dense meteoroid streams in such favourable geometric circumstances could be representative of the organic and water delivery processes that probably participated in the terrestrial enrichment due to the massive disruption of comets that occurred at the time of the Late Heavy Bombardment [4]. Consequently, we put all our effort in studying this presentday rare encounter using the multistation CCD and video monitoring available in the Spanish Meteor Network (SPMN) infrastructure together with additional amateur monitoring stations. SPMN high sensitivity CCD and video cameras were able to record hundreds of meteors that are allowing us to get valuable flux and orbital information on the meteoroids that produced the outburst. Some of the campaign highlights are really astonishing as, for example, the detection of a -11 absolute magnitude Draconid bolide over Andalusia, Spain produced by a 14 kg Giacobinid meteoroid [5]. In this abstract we present some preliminary results on the magnitude of the meteoroid flux arrived to Earth and the first orbits computed so far by our team.