5.2.1 Spectral Resolution

The blue spectrometer operates in 1st and 2nd order. An order-sorting filter blocks the unwanted order. The red spectrometer only operates in 1st order. The spectral resolution of FIFI-LS depends on the observed wavelength. It ranges from R = λ/Δλ ~500 to 2000. That corresponds to a velocity resolution of 150 to 600 km/s. The top panel of Figure 5-3 shows the spectral resolution in velocity resolution and in R vs. wavelength as measured in the lab.

FIFI-LS has 16 pixels in the spectral direction. The wavelength range covered by these 16 pixels also depends on the observing wavelength. The bottom panel of Figure 5-3 shows the instantaneous spectral coverage or bandwidth (BW) in micron.


Spectral Resolution

Instantaneous spectral coverage

Figure 5-3: Top: The spectral resolution in km/s and λ/Δλ for both channels; Bottom: The instantaneous wavelength coverage in km/s of the 16 spectral pixels vs. wavelength.