First results from the 2009-2010 MU radar head echo observation programme for sporadic and shower meteors: the Orionids 2009

Abstract

The aim of this paper is to demonstrate the capabilities of a new automated analysis scheme developed for meteor head echo observations by the Shigaraki middle and upper atmosphere (MU) radar in Japan (N, E). Our analysis procedure computes meteoroid range, velocity and deceleration as functions of time with unprecedented accuracy and precision. This is crucial for estimations of meteoroid mass and orbital parameters, as well as investigations into meteoroid–atmosphere interaction processes. We collected an extensive set of data (>500 h) between 2009 June and 2010 December. Here, we present initial results from data taken in 2009 October 19–21. More than 600 of about 10 000 head echoes recorded during 33 h were associated with the 1P/Halley dust of the Orionid meteor shower. These meteors constitute a very clear enhancement of meteor radiants centred around right ascension α= and declination δ=. Their estimated atmospheric entry velocity of 66.9 km s−1 is in good agreement with 1P/Halley dust ejected in the year 1266 bc, which, according to simulations, crossed Earth’s orbit at the time of our observation. The Orionid activity within the MU radar beam reached about 50 h−1 during radiant culmination. The flux of sporadic meteors in the MU radar data, coming primarily from the direction of the Earth’s apex, peaked at about 700 h−1 during the same observations.