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The initial results of a two year simultaneous optical-radar meteor campaignare described. Analysis of 105 double-station optical meteors having plane ofsky intersection angles greater than 5 degrees and trail lengths in excess of 2km also detected by the Middle Atmosphere Alomar Radar System (MAARSY) as headechoes was performed. These events show a median deviation in radiants betweenradar and optical determinations of 1.5 degrees, with 1/3 of events havingradiant agreement to less than one degree. MAARSY tends to record averagespeeds roughly 0.5 km/s and 1.3 km higher than optical records, in part due tothe higher sensitivity of MAARSY as compared to the optical instruments. Morethan 98% of all head echoes are not detected with the optical system. Usingthis non-detection ratio and the known limiting sensitivity of the cameras, weestimate that the limiting meteoroid detection mass of MAARSY is in the 10-9 kgto 10-10 kg (astronomical limiting meteor magnitudes of +11 to +12) appropriateto speeds from 30-60 km/s. There is a clear trend of higher peak RCS forbrighter meteors between 35 and -30 dBsm. For meteors with similar magnitudes,the MAARSY head echo radar cross-section is larger at higher speeds. Brightermeteors at fixed heights and similar speeds have consistently, on average,larger RCS values, in accordance with established scattering theory. However,our data show RCS ~ v/2, much weaker than the normally assumed RCS ~ v^3, aconsequence of our requiring head echoes to also be detectable optically. Mostevents show a smooth variation of RCS with height broadly following the lightproduction behavior. A significant minority of meteors show large variations inRCS relative to the optical light curve over common height intervals,reflecting fragmentation or possibly differential ablation.

planetary and space science

Simultaneous Optical and Meteor Head Echo measurements using the Middle  Atmosphere Alomar Radar System (MAARSY): Data collection and preliminary  analysis