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Use of interference filters

An important point when observing with TAURUS is that since the interferometer operates at a high order of interference (typically a few hundred), it is necessary to isolate the wavelength region of interest using an order sorting filter. For observations of objects at high redshift, or of unusual emission lines, it is important to check that a filter with a suitable central wavelength is available. Also, the bandwidth of the filter should match the free spectral range of the etalon being used. If the bandwidth of the filter is less than the free spectral range of the etalon, this will restrict the wavelength range covered, whereas if the bandwidth of the filter is much larger than the free spectral range of the etalon, there is a risk of order confusion.


Thu Apr 7 00:29:52 BST 1994