What is the general tradeoff between the instruments spectral resolution and coverage vs. spatial resolution/distribution?
An important trade is between band-pass and sensitivity. The FTS works broad-band, so the in-band photon shot-noise is associated with every spectral channel. A blocking filter reduces the spectral coverage and increases the SNR. For a flat photon spectrum, and shot-noise limited operation, reducing the number of spectral channels increases the SNR in each spectral channel by the square root of the bandwidth reduction factor. The SNR in the pan-chromatic image is reduced by the square root of this factor, since less light is being collected. Simulations suggest that for many DRM programs the scientific value of more spectral channels outweighs the associated decrease in SNR (e.g., measuring photometric redshifts) , and that a likely workhorse operating point would be for R ~ 100. When higher spectral resolution (R=600-10,000) observations of high latitude “blank fields” are required (e.g., for the galaxy evolution DRM), there are too few bright objects to warrant the full spatial multi
