Chapter 4:
Observing with the FGS

4.1 Position Mode Overview

4.1.1 The Position Mode Visit

4.1.2 The Position Mode Exposure

4.2 Planning Position Mode Observations

4.2.1 Target Selection Criteria

4.2.2 Filters

4.2.3 Background

4.2.4 Position Mode Exposure Time Calculations

4.2.5 Exposure Strategies for Special Cases

4.2.6 Sources Against a Bright Background

4.2.7 Crowded Field Sources

4.3 Position Mode Observing Strategies

4.3.1 Summary of Position Mode Error Sources

4.3.2 Drift and Exposure Sequencing

4.3.3 Cross Filter Observations

4.3.4 Moving Target Observation Strategy

4.4 Transfer Mode Overview

4.4.1 The FGS Response to a Binary

4.4.2 The Transfer Mode Exposure

4.5 Planning a Transfer Mode Observation

4.5.1 Target Selection Criteria

4.5.2 Transfer Mode Filter and Color Effects

4.5.3 Signal-to-Noise

4.5.4 Transfer Mode Exposure Time Calculations

4.6 Transfer Mode Observing Strategies

4.6.1 Summary of Transfer Mode Error Sources

4.6.2 Drift Correction

4.6.3 Temporal Variability of the S-Curve

4.6.4 Background and Dark Counts Subtraction

4.6.5 Empirical Roll Angle Determination

4.6.6 Exposure Strategies for Special Cases: Moving Targets