Broadband Filter Imager (BFI)

The Broadband Filter Imager (BFI; Table 1) produces photometric images with broad spectral resolution in 6 bands (CN band, Ca II H line, G band, and 3 continuum bands) at the highest spatial resolution available from the SOT (0.0541 arcsec/pixel sampling) and at rapid cadence (<10 sec typical) over a 218" × 109" FOV. Exposure times are typically 0.03 - 0.8 sec, but longer exposures are possible, if desired. The BFI will allow accurate measurements of horizontal flows and temperature in the photosphere, and measurements in the short wavelength bands will permit identification of sites of strong magnetic field.

Narrowband Filter Imager (NFI)

The Narrowband Filter Imager (NFI; Table 2) provides intensity, Doppler, and full Stokes polarimetric imaging at high spatial resolution (0.08 arcsec/pixel, somewhat coarser sampling than the BFI) in any one of 10 spectral lines (including Fe lines having a range of sensitivity to the Zeeman effect, MgIb, NaD lines, and H-alpha) over the full field of view (328" × 164"). The spectral lines span the photosphere to the lower chromosphere for diagnosis of dynamical behaviour of magnetic and velocity fields at the lower atomosphere. The passband of the Lyot filter is 90 mÅ and the wavelength center is tunable to several positions in a spectral line and its nearby continuum. It is noted that the edges of the full field of view are slightly vignetted due to the limited size of the optical elements of the tunable filter residing in a telecentric beam. The un-vignetted area is 264" in diameter. Exposure times are typically 0.1 - 1.6 sec, but like the BFI, longer exposures are possible.