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.


Current 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

COS2025 Policies

COS Line Spread Functions

HST Spectroscopic Legacy Archive (HSLA)

Airglow Observations


Program Information

COS Instrument Resources

Recent News

Recently Published Documents

Instrument Science Reports (ISRs)


Recently Published ISRs

Listing Results

Results: 5

ISR 2020-08: Cycle 26 COS FUV Dark Monitor Summary

October 02, 2020D. Dashtamirova

ISR 2020-07: Cycle 26 COS FUV Detector Gain Maps

October 02, 2020D. Sahnow

ISR 2020-06: Cycle 26 COS/FUV Spectroscopic Sensitivity Monitor

August 31, 2020R. Sankrit

ISR 2020-05: Testing for Systematics when moving the COS Aperture Block

July 10, 2020A. Fox

ISR 2020-04: Cycle 26 COS NUV Wavelength Scale Monitor

June 16, 2020W. Fischer

View all ISRs

Newsletters (STANs)


Recently Published STANs

Listing Results

Results: 5

October 2020 STAN

October 23, 2020

September 2020 STAN

September 25, 2020

View all STANs

LAST UPDATED: 10/16/2020

Please Contact the HST Help Desk with any Questions