COS Instrument Handbook for Cycle 26 help@stsci.edu

NUV Grating G230L
Description
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.
Special Considerations
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.

 Grating ResolvingPowerR = λ/Δλ Disp. Axis Cross-Disp. Axis G230L 2,100 - 3,900 390 81 ± 1 24.3 24.0 20.3
Figure 13.26: Wavelength Ranges for the G230L Grating
Dark lines represent wavelengths sampled by all four FP-POS positions. Wavelengths above 3200 Å may be contaminated by second-order light.
G230L Point-Source Sensitivity
Table 13.11: G230L Point-Source Sensitivity for PSA
 Wavelength(Å) Throughput Sensitivity(counts pixel-1 sec-1pererg cm-2 sec-1 Å-1) 1400 7.061e-09 7.4e+06 3.19e-04 1600 1.419e-04 1.7e+11 6.42e+00 1800 1.020e-02 1.4e+13 4.61e+02 2000 1.447e-02 2.2e+13 6.55e+02 2200 1.612e-02 2.6e+13 7.29e+02 2400 1.550e-02 2.8e+13 7.01e+02 2600 1.294e-02 2.5e+13 5.85e+02 2800 9.680e-03 2.0e+13 4.38e+02 3000 5.195e-03 1.2e+13 2.35e+02 3200 1.389e-03 3.3e+12 6.29e+01 3400 3.252e-03 8.2e+12 1.47e+02
Figure 13.27: G230L Point-Source Sensitivity for PSA and BOA
G230L Signal-to-Noise Ratio
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 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.