Chapter 7:
Exposure-Time Calculator (ETC)

7.1 The COS Exposure Time Calculators

7.2 Imaging Observations of Red Objects

7.3 Sensitivity, Count Rate, and S/N

7.4 Detector and Sky Backgrounds

7.4.1 Detector Dark Count

7.4.2 Earthshine

7.4.3 Zodiacal Light

7.4.4 Airglow Emission

7.4.5 Tabular Sky Backgrounds

7.5 Extinction Correction

7.6 Examples

7.6.1 A Flat-Spectrum Source

7.6.2 An Early-Type Star

7.6.3 A Solar-Type Star with an Emission Line

7.6.4 A Faint QSO