Abstract
Abstract. We report Geminid meteor head echo observations with the high-power large-aperture (HPLA) Shigaraki middle and upper atmosphere (MU) radar in Japan (34.85° N, 136.10° E). The MU radar observation campaign was conducted from 13 December 2010, 08:00 UTC to 15 December, 20:00 UTC and resulted in 48 h of radar data. A total of ~ 270 Geminids were observed among ~ 8800 meteor head echoes with precisely determined orbits. The Geminid head echo activity is consistent with an earlier peak than the visual Geminid activity determined by the International Meteor Organization (IMO). The observed flux of Geminids is a factor of ~ 3 lower than the previously reported flux of the 2009 Orionids measured with an identical MU~radar setup. We use the observed flux ratio to discuss the relation between the head echo mass–velocity selection effect, the mass distribution indices of meteor showers and the mass threshold of the MU radar.
Highlights
Each year in mid-December, theMEoardtheplaDsGseesevothesrolocugipehmnateifnicttotohbeSsaecsprtoevemcreuodelitadsartrrsymupcesetcctueetrronearao(rrLiafodtihcaoaerfnarideMtnsrgdouoovlreaiidtsgruaiGenal.lel,(omR2DbG0yisn0aeeibe7rdvvo)o.savettNarsie,oleoca2nvDm0siepies0roactm1fnhug,etsrth2eelsiee0iefosn0isGnsc7w,ste)tm.ihthestream of dust giving rise to the Geminid meteor shower. inids contain abundant observational evidence of decreas-The Geminid activity is very stable and has been observed ing meteor magnitude as the every year in mid-December since 1862 (JHonyesd, r1o97l8o).gTyheandshower progresses
In this paper we present Geminid meteor head echo observations using the Shigaraki middle and upper atmosphere (MU) radar in Japan (34.85◦ N, 136.10◦ E)
We have used this value to estimate the cumulative flux of Geminid meteors down to the Geminid mass threshold of the MU radar following the procedure described in Kero et al (2011) for the flux estimation of the 2009 Orionids
Summary
Each year in mid-December, theMEoardtheplaDsGseesevothesrolocugipehmnateifnicttotohbeSsaecsprtoevemcreuodelitadsartrrsymupcesetcctueetrronearao(rrLiafodtihcaoaerfnarideMtnsrgdouoovlreaiidtsgruaiGenal.lel,(omR2DbG0yisn0aeeibe7rdvvo)o.savettNarsie,oleoca2nvDm0siepies0roactm1fnhug,etsrth2eelsiee0iefosn0isGnsc7w,ste)tm.ihthestream of dust giving rise to the Geminid meteor shower. inids contain abundant observational evidence of decreas-. The Geminid activity is very stable and has been observed ing meteor magnitude (increasing meteoroid mass) as the every year in mid-December since 1862 (JHonyesd, r1o97l8o).gTyheandshower progresses. Brown et al (2010) found that the Geminid stream is broader and longer-lived at small radar particle sizes than had previously been appreciated (Sekanina, 1970). It extends from solar longitude 225◦ to 282◦; or roughly from 7 November to 2 January each year.
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