This paper discusses the design and construction of a small spectrograph suitable for photographing the emission, absorption and continuum spectra of stellar objects at visible and near ultraviolet wavelengths. The design utilises a concave diffraction grating which eliminates the need for collimating lenses or mirrors. This results in a fast lightweight instrument with only two reflecting surfaces. The instrument was coupled to the 0.51m Cassegrain 'Mons' telescope at the Teide Observatory in Tenerife, during a Winston Churchill Fellowship visit in August 1991. Spectra were obtained of several objects down to magnitude 6 with a resolution of about 10 Angstrom. Notable results were Vega, where a recognisable spectrum of the hydrogen Balmer absorption lines was obtained with an exposure time of only two seconds, and P Cygni where hydrogen and helium emission lines were recorded. Full design, construction, and operational details are given, together with suggestions for further work, to enable other amateurs to build their own instrument and thus to add a further dimension to their observations.
Journal of the British Astronomical Association
- Pub Date:
- February 1993