HST Data Handbook for WFPC2


A.3 Getting IRAF and STSDAS

Both IRAF and STSDAS are provided free of charge to the astronomical community. You must have IRAF to run STSDAS. Detailed information about installing and retrieving STSDAS is found in the STSDAS Site Manager's Installation Guide and Reference. If you have any problems getting and installing STSDAS, TABLES, or any other packages or data described in this handbook, please contact the Help Desk by sending e-mail to:

A complete description of how to install the synphot data files is provided in section A.3.2.

A.3.1 Retrieving the IRAF and STSDAS Software

There are three ways to get the software:

World Wide Web

The STSDAS World Wide Web page:

provides links and instructions for downloading the appropriate files to your local system or to display the software directory, from which you can select the series of smaller files.

Anonymous FTP

There are two points to remember when using FTP to retrieve STSDAS:

Instructions for installing STSDAS are available in the doc subdirectory of the directory where you find STSDAS. The complete instructions for installing STSDAS, TABLES, and all of the supporting software and reference files (including instrument reference files and the synphot dataset) are found in the STSDAS Site Manager's Installation Guide and Reference.


The software can also be registered and requested using on-line forms available through World Wide Web at the following URL:

When you request the STSDAS software, you can also ask for the appropriate version of IRAF, which will be requested for you- simply check the appropriate box on the form under "Do You Already Have IRAF Installed?" If you prefer to request the IRAF software independent of STSDAS, you can do so by sending e-mail to:

A.3.2 Getting the Synphot Database

This manual sometimes refers to the synphot dataset, which must be available in order to run tasks in the STSDAS synphot package. These data files are not included with the STSDAS software and must be retrieved independently. To do this, you need to retrieve a series of compressed tar files from the STScI FTP site ( in the directory software/stsdas/refdata/synphot. After uncompressing and extracting the tar files (see below), you need to unpack the FITS files as described below.

The synthetic photometry data are read in similar way as the instrument datasets, using the script provided in the top directory. This script is run within IRAF to convert data from FITS format into the format used by the synphot task. This script assumes you have the logical crrefer set up in your extern.pkg file (which is in the directory $iraf/unix/hlib (Unix) or $iraf/vms/hlib (VMS)) or have it set up in your session. You do this by placing the command below in extern.pkg or by typing it on the command line:
set crrefer = "/node/partition/stdata/synphot/"


Figure A.7 shows how to convert the files.

Figure A.7: Unpacking Synthetic Photometry Files

Note that all three synphot files must be unloaded for the script to complete successfully.


A.3.3 Extracting the synphot Unix Tar Files

If you retrieved the synphot database as compressed tar files, you will need to copy them to an appropriate subdirectory and then expand and unpack the files. The tar and compress utilities that do this are are commonly available on most Unix systems, but are not standard in the VMS environment. The examples shown below reflect Unix usage. If you are on a VMS system, you should consult with your systems support staff regarding the availability and usage of these commands. To process the files on a Unix system:

  1. Get the compressed tar file that you want, as described in previous sections.
  2. Make an appropriate subdirectory using the mkdir command.
  3. Pipe the compressed tar file through the uncompress and tar files to expand and unpack the file.

The following example shows how to do this. The example assumes that you are putting the files in a subdirectory under /usr/iraf/stdata (note that the name of your file here is assumed to be XXX.tar.Z).
% pwd
% mkdir XXX
% mv XXX.tar.Z XXX/
% cd XXX
% cat XXX.tar.Z | uncompress | tar -xf -


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