HST Data Handbook for COS

Handbook Structure

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The COS Data Handbook is organized in five chapters, which discuss the following topics:

• Chapter 1:COS Overview provides a brief overview of the instrument and its operational capabilities. If you are not already familiar with the details of COS, you should begin here.
• Chapter 2:COS Data Files describes the contents of COS data files, the meanings of selected header keywords, and the relationship of the data products to the original Phase II proposal. If you are not familiar with the filenames, header keywords, or contents of the data files from COS, you should read this chapter next.
• Chapter 3:COS Calibration describes how the calibration pipeline processes your observation, the content of refernce files used during calibration of your observation and how to run the calibration pipeline from home. If you are not familiar with the important characteristics of COS data and the standard procedures for reducing them, or do not know how your data have been calibrated, you should read this chapter.
• Chapter 4:COS Error Sources describes the sources of uncertainty and limiting accuracies of COS data, with brief discussions of possible on-orbit instrumental phenomena. COS observers should read this chapter to acquaint themselves with the limitations of the data that may remain after pipeline calibration.
• Chapter 5:COS Data Analysis describes certain IRAF/PyRAF/STSDAS tasks, and other software packages useful for optimizing data products and analyzing the data. In particular, it discusses software tools that can be applied to specific types of data and data formats. It describes how to analyze target acquisitions and guide star tracking. It provides descriptions of different kinds of data and gives detailed instructions on how to work with them; specifically: extracted spectra, and TIME-TAG data. Most observers will find this chapter useful when determining how they should reduce and analyze their data.

There are some important pieces of general information about HST data, the HST Archive, and the IRAF and STSDAS analysis software that are not specific to the COS, and which are therefore not discussed in the COS specific section, Part II, of this Data Handbook. We refer the reader to the most recent version of the companion Introduction to HST Data Handbook for this information. In particular, Chapter 1, Chapter 2 and Chapter 3 of the Introduction to HST Data Handbook describe how to retrieve and read HST data, HST file formats, and the basics of the STSDAS software package. Appendix A offers an IRAF primer. Appendix B describes HST file name conventions and exposure "associations". Appendix C describes HST Observation Logs. Additional help with HST data is always available via email to the STScI Help Desk at help@stsci.edu.

Since many of the instrument characteristics may be revised over a short time frame after SM4, readers are advised to consult the COS Web pages (http://www.stsci.edu/hst/cos/) for the latest.