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Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 22 > Chapter 13: Spectroscopic Reference Material > First-Order Grating G140L

First-Order Grating G140L
Description
The G140L grating mode is used with the FUV-MAMA, has a resolving power R~1000, and covers a spectral range from 1150 to 1700 in a single exposure.
Notice, that with two observations, one with G140L and one with G230L, the full spectral region, from 1150 to 3100 can be efficiently observed at an R~1000.
Recommended Uses
The G140L grating mode is designed for observations where high spectral resolution is not required, but efficient, spatially resolved spectroscopy providing wide spectral coverage in the UV is desired.
Figure 13.38: Wavelength Range for the G140L Grating Setting
G140L Sensitivity
Table 13.11: G140L Throughputs & Sensitivities for a Point Source
Figure 13.39: G140L Point Source (left axis) and Diffuse Source (right axis) Sensitivities.
Note
Point source sensitivity assumes full transmission (zero slit losses). Diffuse source sensitivity assumes a 0.1” wide slit. To convert point source sensitivities to diffuse source sensitivities multiply the point source values by the grating spatial plate scale in units of arcseconds per pixel and by the width of the desired slit in units of arcseconds.
G140L Signal-to-Noise
Note:
The top axis displays constant Fλ values corresponding to the STMAG units (V+STMAGλ) on the bottom axis. Recall that STMAG=0 is equivalent to Fλ = 3.63E-9 erg/cm2/s/. The curves are labeled with exposure times in seconds.
 
Figure 13.40: Diffuse Source Signal-to-Noise as a Function of STMAG for G140L
Figure 13.41: Point Source Signal-to-Noise as a Function of STMAG for G140L

Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 22 > Chapter 13: Spectroscopic Reference Material > First-Order Grating G140L

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