Chapter 9:
Exposure-Time Calculations

9.1 Overview

9.1.1 The ACS Exposure Time Calculator

9.2 Determining Count Rates from Sensitivities

9.2.1 Imaging

9.2.2 Spectroscopy

9.3 Computing Exposure Times

9.3.1 Calculating Exposure Times for a Given signal-to-noise

9.3.2 Exposure Time Estimates for Red Targets in F850LP

9.4 Detector and Sky Backgrounds

9.4.1 Detector Backgrounds

9.4.2 Sky Background

9.5 Extinction Correction

9.6 Exposure-Time Examples

9.6.1 Example 1: WFC Imaging a Faint Point Source

9.6.2 Example 2: SBC Objective Prism Spectrum of a UV Spectrophotometric Standard Star

9.6.3 Example 3: WFC VIS Polarimetry of the Jet of M87

9.6.4 Example 4: SBC imaging of Jupiter’s Aurora at Lyman-alpha

9.6.5 Example 5: Coronagraphic imaging of the Beta-Pictoris Disk (The HRC is no longer available)

9.7 Tabular Sky Backgrounds