[Prev][Next][Index][Thread]
(meteorobs) Small Format Meteor Spectroscopy
SMALL FORMAT METEOR SPECTROSCOPY
I have been somewhat reluctant to recommend small format, ie 35mm
cameras for meteor spectroscopy. I have discussed this with Dr. Jiri
Borovicka at Ondrejov, and he thinks it is worth doing.
Many amateurs are using 35 mm type cameras for direct meteor
photography. From a single location, meteor photographs of this type are
interesting, but on the whole provide little information on the meteor
phenomonon. To greatly enhance the value of such photographs, why not add a
transmission grating to these cameras. A 600 groove/mm blazed precision
replica grating mounted on a 50mm fl lens will provide a dispersion of
around 350 angstroms per mm in the first order. Not all that bad. (The
smaller the number, the greater the dispersion). Such gratings are
unfortunately rather expensive. One can however use a so called 750 l/mm
film type, holographic grating such as the type sold by Learning
Technologies Inc. Such a grating will provide a dispersion of around 280
angstroms/mm in the first order. These gratings are not blazed so they are
not as efficient as a precision replica but the cost is a fraction of a
precision replica. They are however a good choice for amateurs interested
in entering the field of meteor spectroscopy. Once bitten by the bug, you
may eventually want to upgrade your spectrographs to larger format and
longer focal length lenses and precision replica gratings. You may even
duplicate the results obtained at Ondrejov Observatory. They have obtained
the spectra of a number of very bright fireballs. One spectacular spectrum,
was measured and over 900 spectral lines were identified. This doesn't
happen very often, but one can hope!!!
Ed Majden - AMS Meteor Spectroscopy Program Coordinator
Follow-Ups: