ABSENCE OF WAKE IN FAINT TELEVISION METEORS

Wake is the degree to which an instantaneous meteor image is spatially distributed. We used a MCP intensified SIT video detector preceeded b y a mechanical rotating shutter to search for wake in a sample of fain t (down to +7.8 apparent magnitude), mainly sporadic meteors. The deta iled analysis of 217 video frames (25 meteors) yielded only one meteor with statistically significant sustained wake. This absence of wake i s consistent with earlier work (Robertson & Hawkes, 1992). The spatial resolution and dynamic range have been improved in the present study. We estimate that wake greater than approximately 200m could have been detected by our observing system, provided that the intensity of wake illumination was at least 1116 that of the main meteor luminosity. We interpret the absence of wake as indicating that most meteors of this size have already disintegrated into constituent grains prior to the beginning of intensive ablation, and that the mass distribution of con stituent grains is fairly narrow (at most a factor of 100 in mass).