Chapter 3: Introduction to ACS 3.1 ACS Location in the HST Focal Plane 3.2 Instrument Capabilities 3.3 Instrument Design 3.3.1 Detectors 3.3.2 ACS Optical Design 3.4 Basic Instrument Operations 3.4.1 Target Acquisitions 3.4.2 Typical ACS Observing Sequence 3.4.3 Data Storage and Transfer 3.5 ACS Quick Reference Guide