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aXe Spectral Extraction

IRAF 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.

概述

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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.

History

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.

Licensing

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.

System design

Four basic components make up the run-time IRAF system:

The Applications Packages are a structured collection of portable tasks for scientific data reduction and analysis, but also for system utilities.

The Command Language (CL) is the default interactive user interface and is also used as scripting language for tasks in the application packages.

The Virtual Operation System (VOS) provides a portable interface for the application tasks. It is modeled after the Unix system functions, but with an API for the IRAF specific Subset Preprocessor language (SPP).

The Host System Interface (HSI) is the kernel providing an interface between the host system and the functions of the VOS. It also provides tools necessary for bootstrapping the system from source. The SPP compiler is also part of the HSI.

Only the HSI is system dependent. All other components are portable by the use of the functions provided by the HSI. This way, porting to a new system requires only changes in this component. However, the initial design was implicitly based on the universal use of 32-bit data types and therefore the port to 64 bit required major efforts not only in the HSI but in all components of the system.

Application packages

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.

System packages

The system packages are located in the base package of IRAF and provide tools for the CL, useful operating system utilities, and basic scientific utilities, f.e. for image processing:
dataio
Data format conversion (FITS, IRAF image format etc.)
images
General bitmap image processing and display
lists
List processing
plot
Vector graphics plotting utilities
softools
Software development and system maintenance tools
system
System utilities
utilities
Miscellaneous utilities, includi

來源：IRAF （CC BY-SA）

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While IRAF is still very popular among astronomers, institutional development and maintenance was stopped. IRAF is now maintained as community software.

History

Licensing

System design

Four basic components make up the run-time IRAF system:

The Applications Packages are a structured collection of portable tasks for scientific data reduction and analysis, but also for system utilities.

The Command Language (CL) is the default interactive user interface and is also used as scripting language for tasks in the application packages.

Application packages

System packages

The system packages are located in the base package of IRAF and provide tools for the CL, useful operating system utilities, and basic scientific utilities, f.e. for image processing:
dataio
Data format conversion (FITS, IRAF image format etc.)
images
General bitmap image processing and display
lists
List processing
plot
Vector graphics plotting utilities
softools
Software development and system maintenance tools
system
System utilities
utilities
Miscellaneous utilities, includi

來源：IRAF （CC BY-SA）

結構化資訊、使用者意見與 AI 擷取的關係會分別標示。

概述

History

Licensing

System design

Application packages

System packages

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文件討論

補充到文件

相關事件檔案

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文件討論

History

Licensing

System design

Application packages

System packages