Астрономиялық деректерді өңдеу және талдау бағдарламалық жиынтығы

Software collection for astronomical data reduction and data analysis

IRAF (Image Reduction and Analysis Facility) is a collection of software written at the National Optical Astronomy Observatory (NOAO) geared towards the reduction of astronomical images and spectra in pixel array form. This is primarily data taken from imaging array detectors such as CCDs. It is available for all major operating systems for mainframes and desktop computers. IRAF was designed cross platform, supporting VMS and UNIX like operating systems. Use on Microsoft Windows was made possible by Cygwin in earlier versions, and can be today done with the Windows Subsystem for Linux. Today, it is primarily used on macOS and Linux. IRAF commands (known as tasks) are organized into package structures. Additional packages may be added to IRAF. Packages may contain other packages. There are many packages available by NOAO and external developers often focusing on a particular branch of research or facility. Functionality available in IRAF includes the calibration of the fluxes and positions of astronomical objects within an image, compensation for sensitivity variations between detector pixels, combination of multiple images or measurement of the redshifts of absorption or emission lines in a spectrum. While IRAF is still very popular among astronomers, institutional development and maintenance was stopped. IRAF is now maintained as community software.

The IRAF project started in fall 1981 at Kitt Peak National Observatory. In 1982, a preliminary design and the first version of the Command Language (CL) were completed. The IRAF Group was founded. Designer of the IRAF system and chief programmer was Doug Tody. In 1983, Space Telescope Science Institute selected IRAF as the environment for their SDAS data analysis system and ported the system to VMS. The first internal IRAF release was in 1984. After a limited distribution of a few outside sites the first public release was 1987. In the middle of the 1990s, the "Open IRAF" project was started to address the problems that were seen at that time. This included language bindings, a way to use IRAF components without the full IRAF environment, new data types and dynamically loadable user code. This project was never completed. At the end of the 1990s, the IRAF development slowed down considerably, as the system was considered mature. The user support was transferred to a Web forum in 2005 and new development of the core system was officially decreased to a very low level. However, voluntary work of the IRAF developers continued and they distributed some unofficial intermediary versions. From 2006 to 2009, a first effort was made to port IRAF to 64 bit at the Institute of Space and Astronautical Science Japan. While this effort did not evolve into a new official IRAF version, it contributed significant portions to the 64 bit port by NOAO. NOAO resumed development efforts in 2007, porting the system to 64 bit and adding Virtual Observatory capabilities to it. This phase ended in 2013 with the release of version 2.16.1. In 2017, the source code was transferred to GitHub. In an effort to package the IRAF software for Debian, it was cleaned up from the remaining non free source code and is maintained solely by the community since then. After a few pre releases, version 2.17 was released in early 2022. 2023, NOIRLab (successor of NOAO) resumed some development and created their own release 2.18 with the scope limited to support the legacy Gemini data reduction pipeline. The relevant changes were later merged into the community release 2.18. +IRAF major versionsVersionRelease dateRemarks2.11984first internal release2.2February 1986limited public release2.3August 14, 1986support for STSDAS2.4October 19, 19862.5July 8, 1987first public release2.6February 24, 19882.7December 4, 19882.8June 30, 19892.9April 10, 19902.10July 7, 19922.11August 27, 19972.12January 25, 20022.132006unofficial releases by NOAO volunteers2.14December 1, 20072.15November 22, 20102.16March 22, 2012last major release by NOAO2.17January 4, 2022first community release2.18April 5, 2024merge of NOIRLab changes

The licensing of IRAF generally follows the MIT license scheme. Older versions contained some non free software. In particular, the NCAR graphics code restricted re distribution of IRAF before it was removed in version 2.16. Also, old versions used code taken from the Numerical Recipes book under a different license. This code was removed or replaced with Open Source in versions after 2.16.1. This allowed the distribution of IRAF packages in mainstream Linux distributions like Debian or Ubuntu.

Application Packages are recursively structured in subpackages and tasks. They can be divided into two classes: general system and basic dataprocessing utilities, and packages specific to astronomical data reduction and analysis. The tasks are dominantly written in SPP and CL.

IRAF allows users to write their own tasks in two main ways. One is by writing non compiled procedure (Command Language, CL) scripts. The second is through compiled subset pre processor (SPP) programs. Tutorial documents exist for both methods.

A full IRAF working environment usually requires two other applications: an extended xterm window with a graphics windows (called xgterm and distributed in a separate x11iraf package) and an image display program referred to as an "image server". The two most popular image servers are SAOImageDS9 (by SAO) and ximtool (NOAO, also distributed in the x11iraf package). As an alternative of xgterm and the Command Language, the Python package PyRAF can be used. PyRAF is able to translate CL scripts into Python scripts. It also provides a graphics window (based on Tk or on Matplotlib). As command shell, either the Python or IPython command shell can be used, or a special mode resembling much of the look and feel of the CL command shell.