Chapter 5:
Spectroscopy with COS

5.1 The Capabilities of COS

5.1.1 First-Order Sensitivity

5.1.2 Sensitivity below 1150 Å

5.1.3 Second-Order Sensitivity

5.1.4 Spectroscopic Resolving Power

5.1.5 Time-Dependent Sensitivity Changes

5.1.6 Zero-Order Image

5.1.7 Internal Scattered Light

5.1.8 Spatial Resolution and Field of View

5.1.9 Photometric (Flux) Precision

5.1.10 Wavelength Accuracy

5.1.11 Vignetting of the NUV Channel

5.2 TIME-TAG vs. ACCUM Mode

5.2.1 TIME-TAG Mode

5.2.2 ACCUM Mode

5.3 Valid Exposure Times

5.4 Estimating the BUFFER-TIME in TIME-TAG Mode

5.4.1 Faint Targets (BUFFER-TIME > Exposure Time)

5.4.2 Bright Targets (BUFFER-TIME < 110 Seconds)

5.4.3 Very Bright Targets (BUFFER-TIME < 80 Seconds)

5.4.4 BUFFER-TIME and AUTO-ADJUST

5.5 Spanning the Gap with Multiple CENWAVE Settings

5.6 FUV Single-Segment Observations

5.7 Internal Wavelength Calibration Exposures

5.7.1 Concurrent Wavelength Calibration with TAGFLASH

5.7.2 AUTO Wavecals (when TAGFLASH is not used)

5.7.3 GO Wavecals (User-specified)

5.7.4 No-Cal Wavecals

5.8 Fixed-Pattern Noise

5.8.1 COS Flat Fielding

5.8.2 Use of Multiple FP-POS Settings

5.9 COS Spectroscopy of Extended Sources

5.10 Wavelength Settings and Ranges