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J. Brit. Astron. Assoc., 109, 2, 1999, p.104
The Random Factory, PO Box 44070, Tucson, AZ 85733-4070, USA. [ http://www.randomfactory.com/lfa.html ]. Two CD set, $81.00 + shipping.
reviewed by Nick James
The most important program running on any computer is its operating system. The operating system provides support for disk files, peripherals (printers, modems, network cards etc.) and some means for humans to interact with the computer. Whilst Microsoft Windows is the dominant operating system in the PC world it may be a surprise to learn that it is not the only choice. Of particular interest to astronomers are the various flavours of free Unix-like systems that have become available in the past few years. Unix first made an appearance in the early seventies but it has been developed over the years and it is now the operating system that most professional astronomers use on their mini-computers and workstations.
There are now quite a few different free Unix systems available for the PC but the most popular one is Linux. The rise of the Linux operating system has been something of a phenomenon recently in computer circles. The core program was written by a Finnish computer science student called Linus Torvalds. Once it was introduced many people freely gave their time and the Internet community developed Linux into the powerful system that we have today.
The installation of Linux on a PC used to be quite a complicated business but it is now relatively straightforward and probably equivalent to the effort involved in installing Windows on a completely empty machine. The disk space available on modern PCs is such that it is quite feasible to have a system that can boot up Windows or Linux depending on the need. Linux can then be configured so that it can see both its own files and the files that live on the Windows disk partitions. In this way it is easy to transfer files from one system to the other.
The advantage of having a Unix-based operating system on your PC is that a whole host of excellent astronomical software utilities become available. These include professional image processing utilities such as IRAF (developed in the US) and the Starlink suite (developed in the UK). Both of these suites contain a wide range of programs. IRAF is probably the most widely used system in the professional community and it has been adopted as the standard software for use in reduction of Hubble Space Telescope data. Since Linux has a growing importance in the PC world drivers for many types of CCD cameras are now available and it is possible to capture images and process them from within the IRAF system. Whilst many of the processing functions found in IRAF programs are also present in Windows-based software there are many that have not yet become available commercially. Even simple functions such as reading and writing FITS format files are often poorly implemented in commercial Windows software. At the other end of the scale IRAF contains a number of image reconstruction algorithms which are either unavailable or very expensive in commercial implementations. It is also possible to add complex batch processing functions based on the IRAF core programs since IRAF contains its own programming language.
Many people may be put off using Unix by the terse command-line interface (a shell in Unix-speak). Unix shells are very powerful but they can be intimidating to the novice user. Things aren't as bad as they seem however since all Unix systems support a graphical user interface (GUI) which is similar to the well-known Windows interface. The Unix GUI is known as X-windows. Systems such as IRAF are command-line based but they use X-windows to provide multiple display windows for image and graphical displays.
The Linux for Astronomy disks contain Linux ports of many professional software suites including IRAF, MIDAS and AIPS. The UK Starlink project also distributes their suite of programs on CD and much of this integrates quite nicely with the IRAF command interface. The LfA disk does not contain any of the Starlink software but this is available free to non-commercial users (contact the undersigned for more details). In addition to all of the astronomy programs the LfA disks contain a complete Linux installation (RedHat 5.1) so they are all you will need to start your experiments with this new system. Whilst all of the software on the LfA disks is available freely on the Net it is often inconvenient to download hundreds of megabytes even with today's very low telecoms costs. The disks give you a convenient local source of the programs with a nicely written GUI installation script. I installed Linux on an old 486 PC using these disks and then installed IRAF and a few other utilities. Everything worked well and there were no unexpected problems.
It amazes me that in the highly-commercialized environment of the late nineties, software of such a high quality as Linux and IRAF should be available free. If you have a basic knowledge of computers you really should investigate the possibilities that Linux presents. The LfA disks provide a single source for all of this material and I would recommend them unreservedly. On the other hand I would not recommend that novice computer users should experiment with Linux. It still remains a system which requires a reasonable knowledge of computers and computing and knowing how to use Microsoft Word on a Windows PC is not a sufficient background!
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