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Photographic and spectrographic observations with a reducing camera on the 61 cm NCU telescope


A Reducing Camera designed by Meinel has been constructed and tested on the 61 cm NCU Cassegrain telescope. The basic principle of RC is to reduce the reflector'sf/13.5 to the equivalentf/2.7 such that the Cassegrain focus image can be reduced on a 35 mm film with almost no loss in sky coverage and in resolution but the exposure time is reduced by a factor of 25. The camera is able to obtain stellar spectra. With a grism and a standard lens the dispersion is 450 Å mm−1, which is comparable to that required for the MK classification. RC constructure and testing results are reported. The method of a wide field spectrograph and that of narrow band differential photography of RC are also discussed.

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Hsin Heng Wu Photographic and spectrographic observations with a reducing camera on the 61 cm NCU telescope. Astrophys Space Sci 118, 415–418 (1986).

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  • Exposure Time
  • Basic Principle
  • Narrow Band
  • Photography
  • Wide Field