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.

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.
COS Handbooks and Documentation
- COS Instrument Handbook
- COS Data Handbook
- COS Walkthrough Notebooks
- COS Newsletters (STANs)
- COS Instrument Science Reports (ISRs)
General Instrument Status
COS/FUV is operating nominally.
COS/NUV is operating nominally.
Helpful Links
HST Spectroscopic Legacy Archive (HSLA)
Program Information
COS Instrument Resources
Recent News
Recently Published Documents
Instrument Science Reports (ISRs)
Filter Results
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April 28, 2025N. Indriolo
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ISR 2025-05: COS/FUV Lifetime Position 5 Target Placement
April 01, 2025E.M. Frazer et al. -
ISR 2025-04: Summary of the Enabling Activities for COS in the LP5 Era
April 01, 2025E. M. Frazer et al. -
ISR 2025-03: The Spectral Extraction Reference Files for COS/FUV G160M at LP6
February 25, 2025E.M. Frazer et al. -
ISR 2025-02: Recommended FP-POS Pairs for Continuous Wavelength Coverage at LP6 for COS FUV
February 24, 2025S. Hasselquist
Newsletters (STANs)
Filter Results
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March 2025 STAN
March 24, 2025 -
January 2025 STAN
January 09, 2025 -
July 2024 STAN
July 15, 2024 -
May 2024 STAN
May 17, 2024 -
March 2024 STAN
March 11, 2024
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HST Help Desk
Please contact the HST Help Desk with any questions.