FUV Grating G140L
Description
G140L is a low-resolution grating (R ~ 2000) with wavelength coverage extending to 900 Å, and perhaps below. Its sensitivity at EUV wavelengths, marked in light blue in Figure 13.14, has not been calibrated. The grating has three central-wavelength settings: 800, 1105, and 1280 Å.
Special Considerations
The gap between Segments A and B spans 105 Å. When settings 800 or 1105 are used, the high voltage on Segment B must be lowered to avoid a dangerously high count rate from zero-order light. Wavelengths longer than 2150 Å may be contaminated by second-order light.
Grating | Resolving Power R = λ/Δλ | Dispersion (mÅ pixel−1) | Plate Scale (milliarcsec pixel−1) | FP-POS Step (Å step−1) | |
---|---|---|---|---|---|
Disp. Axis | Cross-Disp. Axis | ||||
G140L | 1,500–4,000 | 80.3 | 23.0 | 90 | 20.1 |
G140L Point-Source Sensitivity
Table 13.7: G140L Point-Source Sensitivity for PSA.
Wavelength (Å) | Throughput | Sensitivity (counts pixel−1 sec−1 per erg cm−2 sec−1 Å−1) | Effective Area (cm2) |
---|---|---|---|
914 | 1.907e−02 | 1.6e+12 | 1.82e+03 |
950 | 2.701e−04 | 1.5e+12 | 1.75e+03 |
1000 | 2.025e−04 | 1.3e+12 | 1.49e+03 |
1050 | 4.370e−04 | 1.1e+12 | 1.14e+03 |
1100 | 3.869e−02 | 8.6e+11 | 9.00e+02 |
1150 | 2.098e−02 | 6.6e+11 | 6.70e+02 |
1200 | 3.143e−02 | 5.0e+11 | 4 97e+02 |
1250 | 3.481e−02 | 4.2e+11 | 4.01e+02 |
1300 | 3.191e−02 | 3.6e+11 | 3.34e+02 |
1350 | 2.642e−02 | 2.7e+11 | 2.45e+02 |
1400 | 2.117e−02 | 5.4e+12 | 9.58e+02 |
1450 | 1.726e−02 | 4.5e+12 | 7.81e+02 |
1500 | 1.369e−02 | 3.7e+12 | 6.19e+02 |
1550 | 1.052e−02 | 2.9e+12 | 4.76e+02 |
1600 | 8.191e−03 | 2.4e+12 | 3.71e+02 |
1650 | 6.315e−03 | 1.9e+12 | 2.86e+02 |
1700 | 5.209e−03 | 1.6e+12 | 2.36e+02 |
1750 | 4.523e−03 | 1.4e+12 | 2.05e+02 |
1800 | 3.648e−03 | 1.2e+12 | 1.65e+02 |
1850 | 2.789e−03 | 9.3e+11 | 1.26e+02 |
1900 | 1.829e−03 | 6.3e+11 | 8.27e+01 |
1950 | 1.012e−03 | 3.6e+11 | 4.58e+01 |
2000 | 3.978e−04 | 1.4e+11 | 1.80e+01 |
2050 | 1.308e−04 | 4.9e+10 | 5.92e+00 |
2100 | 4.006e−05 | 1.5e+10 | 1.81e+00 |
2148 | 5.357e−06 | 2.1e+09 | 2.42e−01 |
G140L Signal-to-Noise Ratio
-
COS Instrument Handbook
- Acknowledgments
- Chapter 1: An Introduction to COS
-
Chapter 2: Special Considerations for Cycle 29
- • 2.1 COS FUV Detector Lifetime Positions
- • 2.2 Visit Length
- • 2.3 Central Wavelength Settings Added in Cycle 26
- • 2.4 The G285M Grating is Available but Unsupported
- • 2.5 COS Observations Below 1150 Angstroms: Resolution and Wavelength Calibration Issues
- • 2.6 Time-Dependent Sensitivity Changes
- • 2.7 Spectroscopic Use of the Bright Object Aperture
- • 2.8 Non-Optimal Observing Scenarios
- • 2.9 NUV Spectroscopic Acquisitions
- • 2.10 SNAP, TOO, and Unpredictable Source Programs with COS
- • 2.11 Choosing between COS and STIS
- Chapter 3: Description and Performance of the COS Optics
- Chapter 4: Description and Performance of the COS Detectors
-
Chapter 5: Spectroscopy with COS
- • 5.1 The Capabilities of COS
- • 5.2 TIME-TAG vs. ACCUM Mode
- • 5.3 Valid Exposure Times
- • 5.4 Estimating the BUFFER-TIME in TIME-TAG Mode
- • 5.5 Spanning the Gap with Multiple CENWAVE Settings
- • 5.6 FUV Single-Segment Observations
- • 5.7 Internal Wavelength Calibration Exposures
- • 5.8 Fixed-Pattern Noise
- • 5.9 COS Spectroscopy of Extended Sources
- • 5.10 Wavelength Settings and Ranges
- Chapter 6: Imaging with COS
- Chapter 7: Exposure-Time Calculator - ETC
-
Chapter 8: Target Acquisitions
- • 8.1 Introduction
- • 8.2 Target Acquisition Overview
- • 8.3 ACQ SEARCH Acquisition Mode
- • 8.4 ACQ IMAGE Acquisition Mode
- • 8.5 ACQ PEAKXD Acquisition Mode
- • 8.6 ACQ PEAKD Acquisition Mode
- • 8.7 Exposure Times
- • 8.8 Centering Accuracy and Data Quality
- • 8.9 Recommended Parameters for all COS TA Modes
- • 8.10 Special Cases
- Chapter 9: Scheduling Observations
- Chapter 10: Bright-Object Protection
- Chapter 11: Data Products and Data Reduction
-
Chapter 12: The COS Calibration Program
- • 12.1 Introduction
- • 12.2 Ground Testing and Calibration
- • 12.3 SMOV4 Testing and Calibration
- • 12.4 COS Monitoring Programs
- • 12.5 Cycle 17 Calibration Program
- • 12.6 Cycle 18 Calibration Program
- • 12.7 Cycle 19 Calibration Program
- • 12.8 Cycle 20 Calibration Program
- • 12.9 Cycle 21 Calibration Program
- • 12.10 Cycle 22 Calibration Program
- • 12.11 Cycle 23 Calibration Program
- • 12.12 Cycle 24 Calibration Program
- • 12.13 Cycle 25 Calibration Program
- • 12.14 Cycle 26 Calibration Program
- • 12.15 Cycle 27 Calibration Program
- • 12.16 Cycle 28 Calibration Program
- Chapter 13: Spectroscopic Reference Material
- • Glossary