Getting started

In order to get familiar with the FITSH package, we recommend to start your work somehow similar to the following.

Recommended auxiliary software packages

Indeed, FITSH is intended to process the images themselves, however, the package does not contain any utilities to display them or any additional tools for plotting or visualization. Hence, before and/or after installing FITSH, it is advised to get familiar with the following additional packages as well. Of course, you may choose any of your favorite packages or programming environments (for instance, Python or IDL has many of these additional features), but the examples featured in this website mainly expects that these ones are also available in your computer system. In addition these packages are not only free and open source packages but available for almost all of Linux, Mac/OSX or UNIX-like systems as well as on MS/Windows.

• bash. The GNU Bourne-Again SHell, known as bash is one of the most well-known shells found on Linux or UNIX-like operating systems, and it is a de facto standard among the various kind of system shells. Although the FITSH tasks can be executed from any kind of environment, these tasks were designed to be run from bash. Many features of this shell is known by all of Linux or UNIX users, however, we recommend to get familiar with other features, such as conditional or iterative loops, variable definitions, arrays and function declarations as well. Please note that on certain systems, the default shell, /bin/sh not evidently refers the bash shell and hence some features (loops, arrays) work differently. In order to ensure the usage of bash, just start your executable scripts with #!/bin/bash instead of #!/bin/sh (see also the examples section here).
• Gnuplot. Gnuplot is a portable command-line driven plotting utility and can be used to easily visualize the numerical data outputs of the FITSH tasks.
• DS9. The SAOImage/DS9 is the most widely used utility to display and analyze astronomical images that are stored in FITS format. Since the individual tasks of the FITSH package handles this format, we recommend this program to display images.
• XPA. The X Public Access Mechanism (or XPA Messaging System) is the protocol via which external programs can communicate with DS9. If these utilities (mainly, the programs named xpaset and xpaget) are installed to the system, one can easily superimpose FITSH output to the FITS images directly. See e.g. the examples tvmark.sh or imexam.sh that also feature these.
• CDSclient. The Centre de Données astronomiques de Strasbourg (CDS) maintains the most widely used online astronomical catalogue service, the VizieR service. Involving the utilities found in the CDSclient package, we can retrieve these catalogues directly to our system using command line tools.
• wget. Most of the essential features of the CDSclient package can be implemented using purely the wget utility and some bash scripting. In the examples found in this webpage, we present scriptlets that access CDS/VizieR services using purely wget - so, strictly speaking, it is not necessary to install CDSclient -- but it is highly recommended since there are many nice features there which can be useful in your research.
• AWK. The bash scripts presented among the FITSH examples frequently involves AWK scriptlets for various purposes.
• GNU/Coreutils. These examples also uses some tasks from the GNU/Coreutils package, namely programs like sort or uniq.
• pexec. Normally, each FITSH task exploits only a single processor core. Therefore, on multi-processor or multi-core architectures, it is rather effective to do computationally expensive tasks -- image registration, source extraction, image convolution or differential photometry -- in parallel. The utility pexec is a good choice to easily replece shell iterators and loops (for ... in ...; do ...; done or while ...; do ...; done) into a parallel form.

From the above list, bash, gnuplot, wget, (g)awk, GNU/coreutils and pexec are available also as parts of recent Linux distributions and also packaged for other unices (e.g. Mac/OSX, NetBSD) as well. Just use your favorite package manager to install them. The other tools, DS9, XPA, and the CDSclient package can easily be downloaded from their websites. DS9 is available as pre-compiled binary executable, while for the other ones, we can retrieve the source code (which must be compiled and installed thereafter).