HST Data Handbook for COS

Preface

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The HST Data Handbook is composed of three separate sections which are merged together to form a single document:

• Part I is a general introduction which describes the process of retrieving and reducing Hubble Space Telescope (HST) data.
• Part II is an instrument-specific document which describes the reduction procedures, calibrations, and sources of error specific to each HST instrument.
• Part III is a general set of appendices which includes an IRAF primer, a description of HST file names, and a summary of the observation log files.

Use of HST data necessarily involves using software to retrieve, analyze, and view it. With regard to analysis and visualization, there are many different tools and packages available. It would be impractical for a handbook to show how to do this for all available software. Since much of the software developed by STScI for calibrating, analyzing, and visualizing HST data has been based on the IRAF system, and now includes PyRAF, the focus of this handbook will be on use of IRAF/PyRAF, Space Telescope Science Data Analysis System (STSDAS), and TABLES.

Chapter 3 will briefly mention other software tools for accessing HST data and where to get more information about these tools. PyRAF is a new command language (CL) for IRAF and, as such, allows the use of almost all IRAF tools. It is briefly discussed in Chapter 3, but for the most part, the IRAF examples given will work exactly the same in PyRAF.

The specifics of the data produced by the ACS, COS, FGS, NICMOS, STIS, WFC3, and WFPC2 (to be decommissioned during Servicing Mission 4) instruments are described in separate versions of Part II. The general information in Parts I and III, referred to as "the introductory chapters," are appended to the beginning and end of each instrument-specific part. We recommend a careful reading of the introductory chapters before proceeding to the instrument-specific section and before starting to work on your HST data.

The present introductory chapters are based on information available as of December 2008. Changes in the HST Data Archive and data reduction software since then are not included in this revision of the HST Data Handbook introductory chapters.

Future changes in this handbook are anticipated as the Multimission Archive at STScI (MAST) expands to cover additional missions, and as the Hubble Legacy Archive (HLA), PyRAF, and STSDAS software continue to evolve. The reader is advised to consult the STScI Web site at http://www.stsci.edu/hst for the latest information.