WFC3 Data Handbook V. 4.0
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Table of Contents

WFC3 Data Handbook
Acknowledgments
Current Members of the WFC3 Team
Former Members of the WFC3 Team
Thanks
Preface
How to Use this Handbook
Handbook Structure
Typographic Conventions
Visual Cues
Comments
Chapter 1: The WFC3 Instruments
1.1 Instrument Overview
1.2 The UVIS Channel
1.3 The IR Channel
Chapter 2: WFC3 Data Structure
2.1 Types of WFC3 Files
2.1.1 Data Files and Suffixes
2.1.2 Auxiliary Data Files
2.2 WFC3 File Structure
2.2.1 UVIS Channel File Structure
2.2.2 IR Channel File Structure
2.2.3 Contents of Individual Arrays
2.3 Data Storage Requirements
2.4 Headers and Keywords
Chapter 3: WFC3 Data Calibration
3.1 Calibration Overview
3.1.1 Image Processing Summary
3.2 Overview of calwf3
3.2.1 Structure and Processing Flow
3.2.2 UVIS Processing
3.2.3 IR Processing
3.2.4 Running calwf3
3.3 Keyword Usage
3.4 Description of Calibration Steps
3.4.1 wf3ccd
3.4.2 wf32d
3.4.3 wf3ir
3.4.4 wf3rej
3.5 Calibration of WFC3 Spectroscopic Data
3.6 When should I recalibrate my data?
3.7 Manual Recalibration of WFC3 Data
3.7.1 Requirements for Manual Recalibration
3.7.2 calwf3 Examples
Chapter 4: WFC3 Images: Distortion Correction and AstroDrizzle
4.1 WFC3 Geometric Distortion
4.1.1 The IR Channel
4.2 Distortion Corrections and Image Combination
4.2.1 AstroDrizzle in the Pipeline
4.2.2 Manual Reprocessing
4.2.3 AstroDrizzle Documentation
4.3 References
Chapter 5: WFC3-UVIS Sources of Error
5.1 Gain and Read Noise
5.1.1 Gain
5.1.2 Read Noise
5.2 Bias Subtraction
5.2.1 Bias Calibration Issues
5.2.2 Bias Correction for WFC3 Subarrays
5.3 Dark Current, Hot Pixels, and Cosmic Rays
5.3.1 Dark Current
5.3.2 Hot Pixels
5.4 Flat Fields
5.4.1 Ground Flats
5.4.2 On-orbit Corrections
5.4.3 Pipeline Flats
5.5 Image Anomalies
5.5.1 Ghosts
5.5.2 Stray Light
5.5.3 Cross Talk
5.6 Generic Detector and Camera Properties
5.6.1 Full Well Depth
5.6.2 Linearity at Low to Moderate Intensity
5.6.3 Linearity Beyond Saturation
5.6.4 Shutter Stability
5.6.5 Fringing
5.7 References
Chapter 6: Charge Transfer Efficiency (CTE)
6.1 CTE Losses And Background
6.2 The Nature Of CTE Losses
6.3 The Pixel-Based Model
6.4 Empirical Corrections
6.5 Dealing With CTE Losses In WFC3/UVIS Images
6.6 References
Chapter 7: WFC3/IR Sources of Error
7.1 WFC3/IR Error Source Checklist
7.2 WFC3/IR Bias Correction
7.3 WFC3 Dark Current and Banding
7.3.1 Dark Current Subtraction
7.3.2 Banding
7.4 Blobs
7.5 Detector Nonlinearity Issues
7.5.1 Nonlinearity Calibrations
7.5.2 Non-Zero Zeroth Read Correction for Bright Sources
7.6 Count Rate Non-Linearity
7.7 IR Flat Fields
7.7.1 Ground Flats (P-flats)
7.7.2 On-orbit Test of the Ground Flats.
7.7.3 On-orbit L-flats from Sky Observations.
7.7.4 Pipeline Flats
7.8 Pixel Defects and Bad Imaging Regions
7.8.1 Bad Pixels
7.8.2 Non-nominal Detector Regions
7.8.3 Dead Pixels
7.8.4 Bad Zeroth Read Pixels
7.8.5 Unstable Pixels
7.8.6 Snowballs
7.9 Time Variable Background Contamination
7.9.1 Scattered Earthlight
7.9.2 Metastable Helium 1.083 μm Emission Line
7.9.3 Mitigation Strategies
7.10 References
Chapter 8: Persistence
8.1 Image Persistence
8.2 Evaluating the Amount of Persistence in Science Images
8.3 Mitigating the Effects of Persistence
8.4 References
Chapter 9: WFC3 Data Analysis
9.1 STSDAS and STSCI_PYTHON Software
9.2 Photometry
9.2.1 Photometric Systems, Units, and Zeropoints
9.2.2 Aperture and Color Corrections
9.2.3 Pixel Area Maps
9.2.4 CTE
9.2.5 Red Leak
9.2.6 UV Contamination
9.3 Astrometry
9.3.1 Coordinate Transformations
9.3.2 Absolute and Relative Astrometry
9.3.3 Impact of Guide Star Failure
9.4 Spectroscopy
9.4.1 Using the WFC3 Grisms
9.4.2 Pipeline Calibration
9.4.3 Slitless Spectroscopy Data and Dithering
9.4.4 Spectroscopy with the WFC3 G280 Grism
9.4.5 Spectroscopy with the WFC3 IR Grisms
9.4.6 Extracting and Calibrating Slitless Spectra
9.4.7 Reducing WFC3 grism data
9.4.8 Accuracy of Slitless Spectra Wavelength and Flux Calibration
9.5 References
Chapter 10: Spatial Scan Data
10.1 Analysis of Scanned Data
10.2 IR Scanned Data
10.2.1 IR Scanned Spectra
10.3 UVIS Scanned Images
10.4 References

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