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Astronomical Institute

Academy of Sciences of the Czech Republic

Department of Interplanetary Matter

Meteor Physics


TV Meteor Spectra

The use of television techniques instead of the classical photographic method enables scientists to observe fainter meteors and therefore to study smaller members of the meteoroid population. The second advantage is the good temporal resolution. On the other hand, the spatial resolution is lower. The TV spectroscopy of meteors was started by the pioneering work of Millman et al. (1971). Further successful observations were performed in Ashchabad (Mukhamednazarov and Maltseva, 1989). However, in general, relatively small attention has been devoted to the subject and the results published so far are limited to the identification of spectral lines and to the study of the behaviour of the green oxygen line in meteor trains.

At the Ondrejov Observatory, regular TV observations of meteor spectra started in 1990. The limiting magnitude was about +3 and the time resolution was 0.04 s. The observations are being continued during the maxima of major meteor showers with the aim of studying the physics of the meteor phenomenon and to reveal possible chemical and structural differences among the meteoroids of different showers. The presently used instrumentation is summarized in Table. After being digitized by the image processor, the individual frames are analysed by means of a PC.

camera  nightvision model HT 11-22/SIT (Hiradash Technika - Budapest) 
detector  RCA 4804/H SIT-vidicon tube + S 20 photocathode 
lens  Leitz-Noctilux f/1, f=50 mm 
spectral grating  Milton-Roy 300 groves/mm, blazed to 490.0 nm 
frame rate  25 frames/s 
field of view  15 x 11 degrees 
mount  azimuthal 
video recorders  S-VHS GRUNDIG GV 280S, S-VHS PANASONIC NV-FS88, bandwidth > 4 MHz 
image processor  TESLA VUST 
resolution  512 x 512 pixels 
dispersion  1.0 nm/pixel in the first order 

All frames are being dark-frame subtracted and flat-fielded which allows the lines in the spectrum to be readily identified an measured. Since frequently only the higher and overlapping spectral orders are recorded with only a part of the whole spectrum being in the field of view, the correct identification sometimes represents a challenge. Line intensities are influenced by the sensitivity of the detector at different wavelengths. The spectral sensitivity curve was obtained by the observation of spectra of bright standard stars. The spectral window is wide, the lines from 393.3 nm (Ca II) to 868.0 nm (N I) have actually been observed. The maximal sensitivity is between 500-550 nm.

The TV camera is present only in Ondrejov. As the observed meteors are too faint to be recorded by the photographic cameras of the fireball network, no additional information on meteor trajectories and velocities is available. The membership of a particular shower is inferred from the time of appearance, direction of flight and the angular velocity.

The spectral sensitivity of our technique (normalized to unity at 550 nm)
(Adapted from Borovicka, J. and Bocek, J.: Television spectra of meteors, Earth, Moon, and Planets 71, 237-244, 1995)

TVS 74

TV technique is used for observing faint meteors in Ondrejov since 1990 and now more than 100 meteor spectra are recorded. TVS 74 is one of observed spectrum (Orionid, recorded 20/21 X 1994, about +1 mag).

The description of following images and animations is here (the image with commented spectral lines - 57 kB).

You may download images with a step 0.04 s (about 56 kB each):

The animation is available in .avi and .flc formats: All above listed files are stored in our anonymous ftp archive, click here for the direct access to (And recommend it to non-www users.)
Comments to Rosta Stork