Simultaneous radar and video meteors—II: Photometry and ionisation

• We made simultaneous radar and video meteor observations.
• Electron line density and photon radiant power have the same dependence on speed.
• The ratio of ionisation coefficient to luminous efficiency depends on radiant power (and therefore, mass)
• We determine the bolometric luminous efficiency for our dataset: a peak of 5.9% at 41 km/s.
• The total meteoroid mass influx for video sizes (10−510−5 to 10−8kg) is likely overestimated by others.

Simultaneous radar and video measurements of meteors were made using the Canadian Meteor Orbit Radar (CMOR) and several Gen-III image-intensified CCD cameras primarily to relate radar meteor electron line density, q, to video meteor photon radiant power, I  . We find that log10q=log10I+(12.56±0.49)log10q=log10I+(12.56±0.49) leading to M=(38.7±1.2)−2.5log10q, where M is the meteor magnitude in the Gen-III video bandpass (470–850 nm) corresponding to q   at the radar specular point. The ratio of the ionisation coefficient to luminous efficiency, β/τIβ/τI, was estimated from our observations of q/I   to functionally depend on speed and radiant power. For our average meteor photon radiant power of I=64W, we find log10β/τI=(3.00±0.62)log10v−(4.27±1.37)log10β/τI=(3.00±0.62)log10v−(4.27±1.37). By adopting ββ computed according to Jones (1997), which we approximate as log10β=5.84−0.09v0.5−9.56/log10v (roughly proportional to v4 between 20 and 40 km/s), a corresponding estimate of τIτI for our intensified spectral bandpass was made using our measurements of q/I  . We find a peak bolometric value of τI=5.9%τI=5.9% at 41 km/s. The main uncertainties associated with our analysis are the unknown spectra of individual meteors which affect our estimate of absolute radiant power, and uncertain values of the initial trail radius which makes estimates of q   problematic. Our results suggest that the video meteor mass scale is an order of magnitude smaller than previously thought at these higher speeds, and implies that the total meteoroid mass influx between 10−510−5 and 10−8kg is lower than previous studies would suggest.