This is a gadget I picked up for the club and we've had hours of fun using it. It is plastic and designed by Harvard-Smithsonian Center, made by Learning Technologies. When you look in the opening on the narrow end you are looking at a spectrum scale with calibration on the top and on the bottom, the top being eV and the bottom scale being in nm. The scale is on film, about 4" long, curved, and the back is open behind the scale, so it is essentially back lit. To the right is a slit which you point at the light source to read the spectrum. There are calibration instructions which essentially has you slide the scale to the left or right using fluorescent light. On the back of the instrument is a table of spectral lines which identifies 16 elements and their wavelengths to help understand the sources of the emmision and absorbtion lines you will see. Can it be used on a star? I've never tried it, but I think so. The opening is about 5/8" square, and eyepiece projection would probably be the best approach. One would have to figure a way to backlight the scale.
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