Oxygen line in fireball spectra and its application to satellite observations by V. Vojáček et al. on Tuesday 29 November

Aims. Lightning mapper sensors on board weather satellites can be

successfully used to observe fireballs. These sensors use a very narrow

spectral band at 777nm, which is only a small fraction of the total fireball

radiation. In this spectral band, the oxygen O I-1 triplet is dominant for fast

meteors and the Planck continuum can prevail in slow meteors. It is possible to

estimate the meteor brightness in the visible spectral range from this

narrowband radiation, but it is vital to first study the dependence of this

radiation on the meteor velocity. Methods. We used observations from the

well-established European Fireball Network with newly developed digital

spectral cameras that allowed us to study the oxygen triplet in meteor spectra

and its relation to the meteor velocity and altitude. In addition, we studied

strong magnesium and sodium lines. Results. We developed a method for

calibration of fireball observation reported by Geostationary Lightning Mapper

(GLM) sensors on board the Geostationary Operational Environmental Satellite

(GOES) weather satellites. We confirm that in slow meteors, the radiation of

the Planck continuum dominates, but for faster meteors, a correction on

velocity is needed. We observe that the altitude where the oxygen line was

recorded can also affect the radiation at 777 nm. In addition, determining

whether or not the meteor showed a bright flare could also lead to a similar

effect. Thus, the meteor brightness estimate may be impacted by these

characteristics. We derived simple corrections on the altitude and on the

meteor brightness that helped to improve the overall precision of the magnitude

estimate of our sample. This allowed us to estimate the magnitude of meteors

observed by GLM with an accuracy of ~ 1 in magnitude. The Na/Mg line intensity

ratio was found to be constant for velocities above 25 km/s and increasing

toward lower velocities.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.15793v1