Meteor spectra studies started in the 1860s by means of the observations taken by A. Broad spectroscopy programmes were carried out in USA, Canada, the former USSR and Czechoslovakia (Ceplecha et al. New video techniques to study meteor spectra started to be used in the early 1970s (Hemenway et al.
1971), as well as new methods and TV processes for data reduction, described by Millman and Clifton (1975), Borovicka and Bocek (1995) and Zender et al. Meteor spectroscopy is based on the emission of atomic lines (emission spectra), along with other molecular bands and continuous radiation.
The individual PVC protection consists of two concentric tubes whose dimensions fit the CCD and other elements that shape our device.
The PVC tubes only have a 8-mm difference in diameter between them, in the case of spectrograph #1 (96/88 mm) and a 6-mm difference in spectrograph #2 (130/124 mm) as Fig. This lets both tubes fit inside each other and move relative to one another.
Moreover, all the devices that form this system can be controlled at distance and programmed in advance.
The main elements of the spectrographs (CCD cameras, wide-field objectives and diffraction gratings, support and protection) are described below. On the one hand, a Sigma 4.5 mm f/2.8 EX DC HSM objective is attached to the Atik 314L CCD, which provides a 120º field of view and is adapted by a male/female aluminium adapter to achieve a good focus.
We use two different spectrographs, with different optical configurations and CCD cameras, to attempt to get images with different fields of view and sensitivity for the same fireball.
Two CCD cameras with different configurations have been used for each of the spectrographs. On the other hand, a 50 mm f/1.2 Nikon objective that provides a field of view of 15° is also attached to the Atik 11000 CCD via an adapter cap.
Facing each objective and with only a 0.67 mm maximum separation, the 1000 lines per mm holographic grating are connected over a filter adaptor, which varies in each device depending on its size.
Early on, Halliday (1961), Ceplecha (1971) and Borovička (1994a) provided significant identification lists of lines in high-dispersion photographic spectra.
Meteor emission lines can be divided into two components according to their temperature (high and low) (Borovička 1994b).
Search for spectrographic dating:
Each of them is composed by a CCD camera with a wide-field telephoto lens, a holographic diffraction grating and adequate protection against weather (Fig. Both the CCDs and the lenses are different models, and thus, we have had to adopt two different settings in order to obtain two images simultaneously, with different spectral resolution each other.