Cosmic Origins Spectrograph Instrument Handbook for Cycle 17

Chapter 3:
A Tour through COS

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3.1 COS' Location in the HST Focal Plane
3.2 COS' Capabilities
    3.2.1 Signal-to-noise considerations
    3.2.2 Photometric (flux) precision
    3.2.3 Wavelength accuracy
    3.2.4 Sensitivity
    3.2.5 Non-linear photon counting effects (dead-time correction)
3.3 The Design of COS
    3.3.1 Optical Configuration
    3.3.2 Apertures
    3.3.3 The FUV and NUV Channels
    3.3.4 Detectors
    3.3.5 On-board Calibration Lamps
    3.3.6 Mechanisms
3.4 Basic Instrument Operations
    3.4.1 Target acquisitions
    3.4.2 TIME-TAG and ACCUM
    3.4.3 Wavelength calibration
    3.4.4 Typical observing sequences
    3.4.5 Data storage and transfer
3.5 COS Quick Reference Guide

The Cosmic Origins Spectrograph (COS) was built to excel at obtaining low- and medium resolution spectra of faint point sources in the far ultraviolet (FUV). COS was optimized for faint point sources because such objects are the primary targets proposed by COS' Investigation Definition Team (IDT). The COS IDT specifically avoided compromising FUV throughput for the sake of making COS a more general purpose instrument since STIS is intended to fulfill that need.

This chapter provides a brief summary description of COS to help you understand how it operates and can be used. More detailed information is presented in the next several chapters.