|Space Telescope Science Institute|
|COS Instrument Handbook|
The G225M grating samples wavelengths between about 2100 and 2500 Å. The grating has 13 central wavelength settings.G225M spectra consist of three 35 Å stripes separated by two 64 Å gaps. To acquire a complete spectrum requires the use of six central-wavelength settings.
R = λ/Δλ
Spatial Resolution (milliarcsec pixel-1) FP-POS
Figure 13.20: Wavelength Ranges for the G225M GratingTable 13.9: G225M Point-Source Sensitivity for PSA
(counts pixel-1 sec-1 pererg cm-2 sec-1 Å-1)
Effective Area (cm2) Figure 13.21: G225M Point-Source Sensitivity for PSA and BOAFigure 13.22: Point-Source Signal-to-Noise as a Function of STMAG for G225MThe 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 cm-2 s-1 Å-1. Colors refer to exposure times in seconds. The edge of the shaded area corresponds to the bright-object screening limit. Use of the PSA is assumed.