Articles | Volume 6, issue 1
Research article
27 Feb 2017
Research article |  | 27 Feb 2017

Analysis of the technical biases of meteor video cameras used in the CILBO system

Thomas Albin, Detlef Koschny, Sirko Molau, Ralf Srama, and Björn Poppe

Abstract. In this paper, we analyse the technical biases of two intensified video cameras, ICC7 and ICC9, of the double-station meteor camera system CILBO (Canary Island Long-Baseline Observatory). This is done to thoroughly understand the effects of the camera systems on the scientific data analysis. We expect a number of errors or biases that come from the system: instrumental errors, algorithmic errors and statistical errors. We analyse different observational properties, in particular the detected meteor magnitudes, apparent velocities, estimated goodness-of-fit of the astrometric measurements with respect to a great circle and the distortion of the camera.

We find that, due to a loss of sensitivity towards the edges, the cameras detect only about 55 % of the meteors it could detect if it had a constant sensitivity. This detection efficiency is a function of the apparent meteor velocity.

We analyse the optical distortion of the system and the goodness-of-fit of individual meteor position measurements relative to a fitted great circle. The astrometric error is dominated by uncertainties in the measurement of the meteor attributed to blooming, distortion of the meteor image and the development of a wake for some meteors. The distortion of the video images can be neglected.

We compare the results of the two identical camera systems and find systematic differences. For example, the peak magnitude distribution for ICC9 is shifted by about 0.2–0.4 mag towards fainter magnitudes. This can be explained by the different pointing directions of the cameras. Since both cameras monitor the same volume in the atmosphere roughly between the two islands of Tenerife and La Palma, one camera (ICC7) points towards the west, the other one (ICC9) to the east. In particular, in the morning hours the apex source is close to the field-of-view of ICC9. Thus, these meteors appear slower, increasing the dwell time on a pixel. This is favourable for the detection of a meteor of a given magnitude.

Short summary
The Canary Islands Long-Baseline Observatory (CILBO) is a stereoscopic camera setup on the Canary Islands Tenerife and La Palma. Both cameras observe the same volume in the sky to determine high-precision orbits of entering meteoroids. Both cameras are identical; however they show different brightness or velocity distributions of the observed meteors. This work analyses different observational bias effects to determine and understand, e.g. camera pointing or observation time-dependent effects.