Space Telescope Science Institute
COS Instrument Handbook
help@stsci.edu
Table of Contents Previous Next Index Print


Cosmic Origins SpectrographInstrument Handbookfor Cycle 22 > Chapter 13: Spectroscopic Reference Material > NUV Grating G185M

NUV Grating G185M
Description
The G185M grating samples wavelengths between about 1700 and 2100 . The grating has 15 central wavelength settings.
Special Considerations
G185M spectra consist of three 35 stripes separated by two 64 gaps. To acquire a complete spectrum requires the use of six central-wavelength settings.
Resolving
Power
R = λ/Δλ
Dispersion
(m pixel–1)
Spatial Resolution (milliarcsec pixel-1)
FP-POS
Step
( step-1)
Figure 13.17: Wavelength Ranges for the G185M Grating
Dark lines represent wavelengths sampled by all four FP-POS positions.
G165M Point-Source Sensitivity
Table 13.8: G185M Point-Source Sensitivity for PSA
Sensitivity
(counts pixel-1 sec-1 per
erg cm-2 sec-1 -1)
Figure 13.18: G185M Point-Source Sensitivity for PSA and BOA
G185M Signal-to-Noise Ratio
Figure 13.19: Point-Source Signal-to-Noise as a Function of STMAG for G185M
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 -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.

Cosmic Origins SpectrographInstrument Handbookfor Cycle 22 > Chapter 13: Spectroscopic Reference Material > NUV Grating G185M

Table of Contents Previous Next Index Print