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About COS

The Cosmic Origins Spectrograph (COS) was installed on the Hubble Space Telescope (HST) in May 2009. COS performs high-sensitivity, medium- and low-resolution spectroscopy of astronomical objects in the 815-3200 Å wavelength range. COS significantly enhances the spectroscopic capabilities of HST at ultraviolet wavelengths, providing observers with unparalleled opportunities for observing faint sources of ultraviolet light.

The primary science objectives of the instrument are the study of the origins of large scale structure in the Universe, the formation and evolution of galaxies, the origin of stellar and planetary systems, and the cold interstellar medium.

COS spectrum of a massive star in the LMC

This COS spectrum of a massive star in the LMC encodes information about the properties of its stellar wind, the intervening interstellar and circum-galactic media, enabling a wide range of legacy studies.

General Instrument Status 

COS/FUV is operating nominally.

COS/NUV is operating nominally.

Helpful Links

COS Wavelength Tool

HST Exposure Time Calculator

COS Instrument Handbook

COS Data Handbook

COS Walkthrough Notebooks

COS2035 Policies

COS Line Spread Functions

HST Spectroscopic Legacy Archive (HSLA)

Hubble Advanced Spectral Products (HASP)

Airglow Observations

ULLYSES

Program Information

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COS Handbooks and Documentation

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COS Instrument Resources

Quick Links

Recently Published Documents

Instrument Science Reports (ISRs)

Recently Published ISRs

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Newsletters (STANs)

Recently Published STANs

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Last Updated: 07/13/2026

HST Help Desk


Please contact the HST Help Desk with any questions.