12.6 Cycle 18 Calibration Program
The Cycle 18 calibration program continued the calibration and monitoring observations performed in Cycle 17, including long-term programs to monitor the sensitivity and wavelength scale of both the NUV and FUV detectors. Brief descriptions of these monitoring programs are presented in Table 12.2. Table 12.5 lists additional special calibration programs that were undertaken in Cycle 18. A comprehensive review of the Cycle 18 calibration program was published in COS ISR 2013-04 (Kriss et al. 2012).
Table 12.5: Cycle 18 Calibration Program FUV Lifetime Position Calibration Program.
Program ID | Title | Accuracy Achieved | Products |
---|---|---|---|
124141 | COS Observations of Geocoronal Lyman-α Emission | G140L: S/N = 2 per pixel at 1200 Å, | List of exposures on the COS website2 that GOs may use to model and subtract Lyman α |
12426 | FUV Sensitivity Characterization | S/N ~ 10/pixel | ISR, Reference file |
12432 | COS FUV Detector Gain Sag vs. High Voltage | 1% over 2 Å bands | Decision on change of voltage or lifetime position |
1 Coordinated parallel with STIS calibration program 12414.
2 http://www.stsci.edu/hst/instrumentation/cos/calibration/airglow.
As described in Section 4.1.7, gain sag affects spectra obtained with the FUV detector. To address this problem the COS team performed studies to move the Aperture Mechanism so that the FUV spectra fell on a different part of the detector, called a lifetime position. This work was divided into three phases. Table 12.6 lists the programs that were used to determine the location of the new lifetime position, enable science at that location, and finally calibrate observations obtained there. The additional lifetime calibration program "Second COS FUV Lifetime Position: Wavelength Scales (FCAL1)" uses observations from programs 12805, 12806, and 12796.
Table 12.6: Lifetime Position 2 Calibration Program.
| |
12676 | COS/FUV Characterization of Detector Effects |
12677 | COS/FUV Mapping of the Stray PtNe Light through FCA |
12678 | COS/FUV Characterization of Optical Effects |
| |
12793 | Second COS FUV Lifetime Position: FUV Detector High Voltage Sweep (FENA1) |
12795 | Second COS FUV Lifetime Position: Verification of Aperture and FUV Spectrum Placement (FENA2) |
12796 | Second COS FUV Lifetime Position: Focus Sweep Enabling Program (FENA3) |
12797 | Second COS FUV Lifetime Position: FUV Target Acquisition Parameter Update (FENA4) |
| |
12805 | Second COS FUV Lifetime Position: Wavelength and Resolution Calibration (FCAL2) |
12806 | Second COS FUV Lifetime Position: Flux and Flat-field Calibration and TDS Transfer (FCAL3) |
12807 | Second COS FUV Lifetime Position: Verification of FUV BOA Operations (FCAL4) |
Phase I
was part of Cycle 18. Phases II
and III
took place during Cycle 19.
-
COS Instrument Handbook
- Acknowledgments
- Chapter 1: An Introduction to COS
-
Chapter 2: Special Considerations when Observing with COS
- • 2.1 COS FUV Detector Lifetime Positions
- • 2.2 Visit Length
- • 2.3 Central Wavelength Settings Added in Cycle 26
- • 2.4 ORIENT constraints for Extended Sources
- • 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
- • 5.11 Spectroscopy with Available but Unsupported Settings
- 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
- • 12.17 Cycle 29 Calibration Program
- Chapter 13: Spectroscopic Reference Material
- • Glossary