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Hubble Space Telescope
STIS Spectral Resolution

Spectral resolution is crudely characterized by the FWHM (in pixels) of an unresolved spectral line.

Spectral Resolution (FWHM) Tables

Detector Gratings
MAMA G140L, G230L, G140M, G230M
MAMA E140M, E230M
MAMA E140H, E230H
CCD G430L, G750L, G430M, G750M

For point sources, FWHM is relatively insensitive to aperture width, but spectral purity degrades with increasing aperture width.

Line Spread Functions (LSF) or instrumental profiles give the detailed distribution of light along the primary dispersion axis.

Line Spread Function Plots

Detector Gratings
MAMA G140L, G230L, G140M, G230M
MAMA E140M, E230M
MAMA E140H, E230H
CCD G430L, G750L, G430M, G750M

Tabulated Line Spread Functions

1200 Å 1500 Å 1700 Å 2400 Å 3200 Å 5500 Å 7000 Å
G140L G140L G230L G230L G430L G430L G750L
G140M G140M G230M G230M G430M G430M G750M
E140M E140M E230M E230M      
E140H E140H E230H E230H      

Turning off the FUV-MAMA repeller reduces LSF wings, but use of this available mode requires a strong scientific justification.