Wide Field Camera 3 Instrument Handbook for Cycle 19 - Space ...

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Table of Contents
9.6 Estimating Exposure Times ...............................................160
9.6.1 S/N Reached in a Given Exposure Time ...........................160
9.6.2 Exposure Time to Reach a Given S/N ...............................161
9.6.3 Exposure Time Estimates for Red Targets in F850LP ......162
9.7 Sky Background ....................................................................162
9.7.1 Background Variations and LOW-SKY ............................165
9.7.2 Geocoronal Emission and SHADOW................................168
9.8 Interstellar Extinction ..........................................................168
9.9 Exposure-Time Calculation Examples............................168
9.9.1 Example 1: UVIS Imaging of a Faint Point Source...........169
9.9.2 Example 2: IR Imaging of a Faint Extended Source .........169
9.9.3 Example 3: Imaging an HII region in M83 in Hα .............170
Chapter 10: Overheads and Orbit
Time Determinations.....................................................172
10.1 Overview...............................................................................172
10.2 Observatory Overheads.....................................................173
10.3 Instrument Overheads........................................................175
10.3.1 Exposure Overheads ........................................................175
10.3.2 Reducing Overheads with Subarrays and Binning ..........178
10.4 Orbit Use Examples ...........................................................179
10.4.1 Example 1: UVIS, 1 orbit, 1 filter ...................................179
10.4.2 Example 2: UVIS, 1 orbit, short exposures .....................180
10.4.3 Example 3: IR, 1 orbit, 2 filters .......................................181
10.4.4 Example 4: UVIS, dithering, 2 orbits, 1 filter .................182
10.4.5 Example 5: IR, 1 orbit, grism ..........................................183
Appendix A: WFC3 Filter Throughputs ...........185
A.1 Introduction ............................................................................186
A.2 Throughputs and S/N Ratio Data......................................186
A.2.1 Sensitivity Units and Conversions .....................................186
A.2.2 Signal-to-Noise Ratio.........................................................187
Appendix B: Geometric Distortion.........................275
B.1 Overview .................................................................................275
B.2 UVIS Channel ........................................................................276
B.3 IR Channel ..............................................................................278
B.4 Summary..................................................................................280