1.1 Overview
The Cosmic Origins Spectrograph (COS) was installed on the Hubble Space Telescope (HST) in May 2009. Working at far-ultraviolet wavelengths, COS was designed to study the origins of large-scale structure in the Universe, the formation and evolution of galaxies, the origin of stellar and planetary systems, and the cold interstellar medium. COS significantly enhances the spectroscopic capabilities of HST at ultraviolet wavelengths, and provides observers with unparalleled opportunities for observing faint sources of ultraviolet light.
COS offers two independent observing channels, a far-ultraviolet (FUV) detector, which is sensitive to wavelengths between 900 and 2150 Å, and a near-ultraviolet (NUV) detector for wavelengths from 1650 to 3200 Å. Both channels are equipped with medium-resolution (R ~ 20,000) and low-resolution (R ~ 3000) gratings. The NUV channel can also be used in imaging mode for both target acquisitions and scientific observations. The COS field of view is approximately 2.5 arcsec in diameter.
In this chapter, we provide a brief overview of COS operations, tables of instrument and detector parameters, a list of frequently-asked questions, and a guide to using this handbook.
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COS Instrument Handbook
- Acknowledgments
- Chapter 1: An Introduction to COS
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Chapter 2: Special Considerations for Cycle 28
- • 2.1 COS FUV Detector Lifetime Positions
- • 2.2 Central Wavelength Settings Added in Cycle 26
- • 2.3 Use of the G285M Grating is Discouraged
- • 2.4 COS Observations Below 1150 Angstroms: Resolution and Wavelength Calibration Issues
- • 2.5 Time-Dependent Sensitivity Changes
- • 2.6 Spectroscopic Use of the Bright Object Aperture
- • 2.7 Non-Optimal Observing Scenarios
- • 2.8 NUV Spectroscopic Acquisitions
- • 2.9 SNAP, TOO, and Unpredictable Source Programs with COS
- • 2.10 Choosing between COS and STIS
- Chapter 3: Description and Performance of the COS Optics
- Chapter 4: Description and Performance of the COS Detectors
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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
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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
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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
- Chapter 13: Spectroscopic Reference Material
- • Glossary