Space Telescope Science Institute
COS Data Handbook v.3
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Table of Contents

COS Data Handbook
List of Figures
List of Tables
How to Use this Handbook
Handbook Structure
Typographic Conventions
Visual Cues
Chapter 1: COS Overview
1.1 Instrument Capabilities and Design
FUV Spectroscopy
NUV Spectroscopy
Grating Offset Positions (FP-POS)
NUV Imaging
Data Collection Modes
1.2 COS Physical Configuration
1.2.1 The COS Detectors
1.3 Basic Instrument Operations
1.3.1 Target Acquisitions
1.3.2 Routine Wavecals
1.3.3 Typical COS Observing Sequence
1.4 COS Coordinate System
Chapter 2: COS Data Files
2.1 Overview
2.2 COS File Names
2.3 COS File Structures
2.3.1 COS FITS Table Extension Files
2.3.2 COS FITS Image Extension Files
2.4 COS Data Products
2.4.1 Uncalibrated Science Data Files
2.4.2 Intermediate Science Data Files
2.4.3 Final Science Data Files (and Product Files)
2.4.4 Auxiliary Data Files
2.5 Data Storage Requirements
2.6 Headers, Keywords, and Relationship to Phase II
2.7 Error and Data Quality Array
2.7.1 Error Array
2.7.2 Data Quality Flags
Chapter 3: COS Calibration
3.1 Raw Data Compilation
3.2 Pipeline Processing Overview
3.2.1 Overview of TWOZONE extraction
3.2.2 Extended Sources
3.3 Calcos: Structure and Data Flow
3.4 Descriptions of Spectroscopic Calibration Steps
3.4.1 Initialization
3.4.2 BADTCORR: Bad Time Intervals
3.4.3 RANDCORR: Add Pseudo-Random Numbers to Pixel Coordinates
3.4.4 TEMPCORR: Temperature-Dependent Distortion Correction
3.4.5 GEOCORR and IGEOCORR: Geometric Distortion Correction
3.4.6 WALKCORR: Walk Correction
3.4.7 DEADCORR: Nonlinearity Correction
3.4.8 PHACORR: Pulse Height Filter
3.4.9 DOPPCORR: Correct for Doppler Shift
3.4.10 FLATCORR: Flat-field Correction
3.4.11 WAVECORR: Wavecal Correction
3.4.12 BRSTCORR: Search for and Flag Bursts
3.4.13 TRCECORR: Apply Trace Correction
3.4.14 ALGNCORR: Alignment Correction
3.4.15 DQICORR: Initialize Data Quality File
3.4.16 STATFLAG: Report Simple Statistics
3.4.17 X1DCORR: Locate and Extract 1-D Spectrum
3.4.18 BACKCORR: 1D Spectral Background Subtraction
3.4.19 FLUXCORR/TDSCORR: Conversion to Flux
3.4.20 HELCORR: Correction to Heliocentric Reference Frame
3.4.21 Finalization (making the x1dsum files)
3.5 Descriptions of Imaging Calibration Steps
3.6 Customizing COS Data Calibration
3.6.1 Mechanics of Tailored Recalibration
3.6.2 Using GO Wavecals
3.6.3 Customizing the TWOZONE extraction
3.7 Reference Files
3.7.1 BADTTAB: Bad Time Interval Table
3.7.2 BRFTAB: Baseline Reference Frame Table
3.7.3 GEOFILE: Geometric Correction File
3.7.4 WALKTAB: Y Walk Correction Table
3.7.5 DEADTAB: Deadtime Table
3.7.6 PHATAB: Pulse Height Discrimination Table
3.7.7 PHAFILE: Pulse Height Discrimination File
3.7.8 FLATFILE: Flat-field File
3.7.9 LAMPTAB: Template Calibration Lamp Spectra Table
3.7.10 DISPTAB: Dispersion Coefficient Table
3.7.11 XTRACTAB: 1-D Spectral Extraction Table
3.7.12 BRSTTAB: Burst Parameters Table
3.7.13 BPIXTAB: Bad Pixel Table
3.7.14 GSAGTAB: Gain Sag Table
3.7.15 SPOTTAB: Hotspot Table
3.7.16 WCPTAB: Wavecal Parameter Table
3.7.17 FLUXTAB: Photometric Throughput Table
3.7.18 TDSTAB: Time Dependent Sensitivity Table
3.7.19 TRACETAB: Trace Correction Table
3.7.20 PROFTAB: Profile Table
3.7.21 TWOZXTAB: TWOZONE Spectral Extraction Table
3.7.22 SPWCSTAB: Spectroscopic WCS Parameters Table
Chapter 4: COS Error Sources
4.1 Overview
4.2 Error Sources Associated with Pipeline Processing Steps
4.2.1 FUV Dark Count Rate
4.2.2 Flat Fields
4.2.3 Gain Sag
4.2.4 FUV XDL Thermal Drifts
4.3 Factors Limiting Flux and Wavelength Accuracy
4.3.1 Flux Accuracy
4.3.2 Wavelength and Spectral Resolution Accuracies
Chapter 5: COS Data Analysis
5.1 Data Reduction and Analysis Applications
5.1.1 COS-Specific STSDAS Tasks
5.1.2 FITS Table Tasks
5.1.3 General Spectral Display and Analysis Tasks
5.2 Evaluating Target Acquisitions and Guiding
5.2.1 Types of Target Acquisitions
Undispersed Light (Imaging) Acquisitions (ACQ/IMAGE)
Dispersed-Light Acquisitions (ACQ/PEAKD and ACQ/PEAKXD)
5.2.2 Guiding Errors for Single-Guide-Star Mode
5.3 Working with Extracted Spectra
5.3.1 Working With x1d Files in IDL
5.3.2 Working With x1d Files in Python
5.3.3 Working With x1d Files in IRAF/PyRAF
5.3.4 Redoing Spectral Extraction
5.3.5 Splicing Extracted Spectra
5.4 Working with TIME-TAG Data
5.4.1 Displaying TIME-TAG Data in DS9
5.4.2 Filtering Time-Tag Data
Appendix A: COS New Lifetime Position
A.1 COS New Lifetime Position
Appendix B: COS High Voltage
B.1 COS High Voltage History

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