HST Data Handbook for WFPC2

3.1 Navigating STSDAS

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The tasks in STSDAS are far too numerous and complicated to describe comprehensively in this volume. Instead, we will show you where to find the STSDAS tasks appropriate for handling certain jobs. You can refer to online help or the STSDAS User's Guide for details on how to use these tasks. Some useful online help commands are:

• help task - provides detailed descriptions and examples of each task.
• help package - lists the tasks in a given package and their functions.
• describe task - provides a detailed description of each task.
• example task - provides examples of each task.
• apropos word - searches the online help database for tasks relating to the specified word (see figure A.4).

3.1.1 STSDAS Structure

STSDAS is structured so that related tasks are grouped together as packages. For example, tasks used in the calibration process can be found in the hst_calib package and tasks used for image display and plotting can be found in the graphics pack. Figure 3.1 shows the STSDAS package structure. Note that IRAF version 2.11 must be installed on your system in order for you to use STSDAS 2.0 and TABLES version 2.0 or higher 

3.1.2 Packages of General Interest

Images

Both IRAF and STSDAS contain a large number of tasks that work with HST images. Some of the packages you should investigate are:

• images: This package includes general tasks for copying (imcopy), moving (imrename), and deleting (imdelete) image files. These tasks operate on both the header and data portions of the image. The package also contains a number of general purpose tasks for operations such as rotating and magnifying images.
• stsdas.toolbox.imgtools: This package contains general tools for working with multigroup GEIS images, including tasks for working with masks, and general purpose tasks for working with the pixel data, such as an interactive pixel editor (pixedit).
• stsdas.toolbox.imgtools.mstools: This package contains tools for working with FITS image extensions, in particular STIS and NICMOS image sets (imsets).
• stsdas.analysis: This package contains general tasks for image analysis, such as Fourier analysis and dither.

Tables

Several of the analysis packages in STSDAS, including calibration pipeline tasks, create output files in STSDAS table format, which is a binary row-column format, or in FITS binary table format. (ASCII-format tables are also supported, for input only.) The STSDAS User's Guide describes the STSDAS table format in detail. Tasks in the ttools package or in the external tables package can be used to read, edit, create, and manipulate tables. For example:

• tread displays a table, allowing you to move through it with the arrow keys.
• tprint displays a table.
• tcopy copies tables.
• tedit allows you to edit a table.

Many other tasks in ttools perform a variety of other functions. See the online help for details.