|COS Instrument Handbook for Cycle 25|
The G285M grating samples wavelengths between about 2500 and 3200 Å. The grating has 17 central wavelength settings.G285M spectra consist of three 41 Å stripes separated by two 74 Å gaps. To acquire a complete spectrum requires the use of eight central-wavelength settings.
R = λ/Δλ
Figure 13.23: Wavelength Ranges for the G285M GratingTable 13.10: G285M Point-Source Sensitivity for PSA
(counts pixel-1 sec-1 pererg cm-2 sec-1 Å-1)
Figure 13.24: G285M 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.