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Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 22 > Chapter 13: Spectroscopic Reference Material > Echelle Grating E230M

Echelle Grating E230M
Description
The E230M grating is used with the NUV-MAMA and provides echelle spectra at a resolving power of 30,000 from 1605 to 3100 .
Special Considerations
A single exposure with this grating covers 800 over ~20-40 orders. The interorder separation is ~18 pixels (0.52 arcseconds) at 1650 and 62.5 pixels (~1.8 arcseconds) at 3100 . The grating must be scanned, with exposures taken at two distinct settings to cover the full spectral range of the grating.
 
λ/60,000
Figure 13.46: Wavelength Ranges for the E230M Grating Settings
E230M Sensitivities
Table 13.13: E230M Throughputs & Sensitivities for a Point Source
Figure 13.47: E230M Point Source (left axis), and Diffuse Source (right axis) Sensitivities. Throughput curve traces the peaks of the blaze function for each order.
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 (cross dispersion) plate scale in units of arcseconds per pixel and by the width of the desired slit in units of arcseconds.
E230M 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 13.48: Diffuse Source Signal-to-Noise as a function of STMAG for E230M
Figure 13.49: Point Source Signal-to-Noise as a Function of STMAG for E230M

Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 22 > Chapter 13: Spectroscopic Reference Material > Echelle Grating E230M

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