WFC3 Instrument Handbook for Cycle 24

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Chapter 6:
UVIS Imaging with WFC3

6.1 WFC3 UVIS Imaging

6.2 Specifying a UVIS Observation

6.3 UVIS Channel Characteristics

6.4 UVIS Field Geometry

6.4.1 Field of View and Pixel Size

6.4.2 Geometric Distortion

6.4.3 Coordinate Systems

6.4.4 Subarrays and On-Chip Binning

6.4.5 Apertures

6.5 UVIS Spectral Elements

6.5.1 Filter and Grism Summary

6.5.2 Filter Red Leaks

6.5.3 Ghosts

6.6 UVIS Optical Performance

6.6.1 PSF Width and Sharpness

6.6.2 Encircled and Ensquared Energy

6.6.3 Other PSF Behavior and Characteristics

6.7 UVIS Exposure and Readout

6.7.1 Exposure Time

6.7.2 ACCUM Mode

6.8 UVIS Sensitivity

6.8.1 Limiting Magnitudes

6.9 Charge Transfer Efficiency

6.9.1 Overview

6.9.2 CTE-Loss Mitigation Before Data Acquisition: Observation Planning

6.9.3 CTE-Loss Mitigation After Data Acquisition: Post-Observation Image Corrections

6.10 Photometric Calibration

6.11 Other Considerations for UVIS Imaging

6.11.1 Gain and Full-Well Saturation

6.11.2 Cosmic Rays and Hot Pixels

6.11.3 Image Persistence

6.11.4 Shutter-Induced Vibration

6.11.5 Droplets

6.11.6 Optical Anomalies

6.12 UVIS Observing Strategies

6.12.1 Dithering Strategies

6.12.2 Parallel Observations

6.12.3 Spatial Scans

6.12.4 PSF Subtraction