How to Use this Handbook

This handbook is designed to help users manipulate, process, and analyze data from the Cosmic Origins Spectrograph (COS), which was installed on the Hubble Space Telescope (HST) during the 2009 servicing mission (SM4). It is designed for users familiar with HST data but new to COS.

The current edition of the COS Data Handbook was published in August 2021. It is presented as an independent and self-contained document, referred to as the COS Data Handbook.

For detailed information on the capabilities of the instrument, and how to plan observations, users should refer to the COS Instrument Handbook. For further information and timely updates, users should consult the COS Web page (, especially the Document Archive link. In particular, the STScI Analysis Newsletters (STANs) highlight changes in code and calibration procedures and provide other instrument-related news. The Instrument Science Reports (ISRs) present in-depth characterizations of the instrument and detailed explanations of calibration code and procedures.