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Handbook Structure

This edition of the HST Data Handbook is organized into two volumes. Volume 1 provides general information on retreiving and reducing HST data and includes the more specific information needed to analyze data from the instruments currently on board the spacecraft (FOC, FGS, NICMOS, STIS, and WFPC2). Volume 2 covers the instruments that have been retired (FOS, GHRS, HSP, and WF/PC-1).

Part 1 of Volume 1 leads observers through the following three-step process, applicable to HST data files from any instrument:

Chapter 1 on Getting HST Data demonstrates how to search the HST Archive for proprietary observations or other observations of interest and to download them to your machine. If you already know how to search for and download HST data, or if all the data files you need are present on your disk, you can skip Chapter 1.
Chapter 2 on HST File Formats describes the FITS and GEIS formats used for transferring and reducing HST data. It explains how HST data are stored in these files and shows how to access these data. STIS and NICMOS observers especially should read this chapter, as the procedures for accessing these data differ from those for other instruments. Observers working with FOC, FOS, FGS, GHRS, HSP, WF/PC-1, or WFPC2 data will need to convert the FITS files they receive from the Archive into GEIS format, and section 2.3 shows how to perform this conversion. If you are not using STIS or NICMOS data and are already familiar with the standard GEIS format for HST data, you can skip Chapter 2.
Chapter 3 on STSDAS Basics introduces you to some software packages designed specifically for HST data and gives a few examples. If you are already familiar with STSDAS, you can skip this chapter and proceed to the relevant instrument chapters.

Parts 2 through 10 present five-chapter sequences on each HST instrument, consisting of the following topics:
Instrument Overview, providing a fundamental understanding of the instrument and the vocabulary associated with it. If you are not already familiar with the details of your chosen instrument, you should begin here.
Data Structures, describing the contents of the various 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 this particular instrument, you should read this chapter next.
Calibration, describing how the calibration pipeline processes your observations before they enter the Archive, how to determine if your data files need recalibration, and how to recalibrate them. If you do not know how your data have been calibrated, you should read this chapter.
Error Sources, describing the various sources of error afflicting pipeline calibrated data. All observers using a given instrument should read this chapter to acquaint themselves with the peculiarities of the data that remain after pipeline -calibration.
Data Analysis, describing certain methods and IRAF/STSDAS tasks for analyzing the data. Most observers will find this chapter useful when determining how they should reduce their data.

Five Appendixes to this handbook, found in Volume 1, provide some additional general information that you might find useful:
Appendix A, the IRAF Primer, is an introduction to IRAF and is intended for those who have no prior experience with this data reduction software.
Appendix B, on HST File Names, shows how to interpret the names of the files you receive from the Archive and explains why certain STIS and -NICMOS observations belong to associations of exposures.
Appendix C, on Observation Logs, discusses the files created by the -Observatory Monitoring System (OMS); these files record information on guiding, such as spacecraft jitter, during a given observation.
Appendix D, the Task Example Index, provides pointers to the examples of various IRAF/STSDAS tasks scattered throughout the book.
Appendix E, listing Resources on the Internet, indicates where you can access some of the many valuable tools and documents available through the STScI Web pages.

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