HDS slit viewer
HDS incorporates a slit viewer which takes light reflected off the slit and feeds it to a 512 x 512 pixel CCD. The slit viewer provides a 60'' diameter field of view.
Three filters are available in the slit viewer: standard V and R filters, and a neutral density (ND2=1% or ND4=0.01%) filter. And, a special band-pass filter BP530 (center wavelength : 529nm, FWHM : 39nm), which is optimzed for I2-cell absorption wavelength, is also avairable. On a dark, clear night, objects as faint as 20th magnitude can be seen with 2-5sec exposure of the slit viewer; with the ND4 filter, a 1st magnitude object will not saturate.
More detailed performance figures for the slit viewer will be given here when available.