|Space Telescope Science Institute|
|COS Instrument Handbook Cycle 23|
G230L is a low-resolution grating (R~3000) with wavelength coverage extending from about 1650 to 3200 Å. The grating has four central-wavelength settings.G230L spectra consist of three 400-Å stripes separated by two 700-Å gaps. To acquire a complete spectrum requires the use of all four central-wavelength settings.Only stripes A and B record first-order light, and even they may be contaminated by second-order light when central wavelength 3360 is used. See Table 5.4.
R = λ/Δλ
Figure 13.26: Wavelength Ranges for the G230L GratingDark lines represent wavelengths sampled by all four FP-POS positions. Wavelengths above 3200 Å may be contaminated by second-order light.Table 13.11: G230L Point-Source Sensitivity for PSA
(counts pixel-1 sec-1
erg cm-2 sec-1 Å-1)
Figure 13.27: G230L Point-Source Sensitivity for PSA and BOAThe 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.