KASI and Seoul National University developed the Fast Imaging Solar Spectrograph (FISS) as one of major scientific instruments for the 1.6 m New Solar Telescope (NST) and installed it in the Coude room of the NST at Big Bear Solar Observatory (BBSO) in May, 2010. The major objective of the FISS is to study the fine-scale structures and dynamics of plasma in the photosphere and chromosphere. To achieve it, the FISS is required to take data with a spectral resolution higher than 105 at the spectrograph mode and a temporal resolution less than 10 seconds at the imaging mode. The FISS is a spectrograph using Echelle grating and has characteristics that can observe dual bands (Hα and CaII 8542) simultaneously and perform fast imaging using fast raster scan and two fast CCD cameras. In this paper, we introduce briefly the whole process of FISS development from the requirement analysis to the first observations.

Spectral line profiles of filaments/prominences to be observed by the Fast Imaging Solar Spectrograph (FISS) are studied. The main spectral lines of interests are Hα Ca II 8542, and Ca II K. FISS has a high spectral resolving power of 2 x 105, and supports simultaneous dual-band recording. This instrument will be installed at the 1.6m New Solar Telescope (NST) of Big Bear Solar Observatory, which has a high spatial resolution of 0.065" at 500nm. Adopting the cloud model of radiative transfer and using the model parameters inferred from pre-existing observations, we have simulated a set of spectral profiles of the lines that are emitted by a filament on the disk or a prominence at the limb. Taking into account the parameters of the instrument, we have estimated the photon count to be recorded by the CCD cameras, the signal-to-noise ratios, and so on. We have also found that FISS is suitable for the study of multi-velocity threads in filaments if the spectral profiles of Ca II lines are recorded together with Hα lines