Siril is a software application for astrophotography, which allows pre-processing and processing of images from any type of camera (CCD, planetary camera, webcam etc.). The images must be converted to

32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculation ...

FITS Flexible Image Transport System (FITS) is an open standard defining a digital file format useful for storage, transmission and processing of data: formatted as multi-dimensional arrays (for example a 2D image), or tables. FITS is the most com ...

format which is the format used natively by Siril. It is also possible to use the SER format (limited to 16 bits), generally used during "fast" planetary or

deep sky A deep-sky object (DSO) is any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed fa ...

acquisitions, without prior conversion. It is based on the

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environment and therefore can be run on many systems like Linux,

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, MacOS, and Windows. It is free software distributed under the terms of the

GNU GPL The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general us ...

History

The project was launched in 2005 by François Meyer. Siril was initially developed as a clone of Christian Buil's IRIS software, in order to overcome the lack of astronomical image processing software under the Linux system; hence the name SIRI-L (IRIS for Linux). A new team took over development of the project in 2012 after a pause from 2007.

Features

Siril allows the conversion of a large number of formats (images or videos) to

. * The calibration, alignment and stacking of astronomical images is done by navigating through the tabs of the "control center". However, an algorithm for the automatic detection and correction of defective pixels is available off the tab, in the Image processing menu. * Since version 0.9.7, the global alignment which uses a recognized algorithm for this task has been added an optimization method thanks to the OpenCV library. In fact, Siril's automatic alignment allows to align images obtained with instruments of different

focal length The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...

s. * Some image processing algorithms are available in the standard menu, such as Histogram Transformation, Color Calibration, and Banding Reduction * Siril has a photometric analysis tool. Therefore, it is possible to study the transits of

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

s, the variability of stars or even occultations. This tool requires the installation of gnuplot. * Since version 0.9.9, the ability to create scripts has been integrated into Siril. All you have to do is drop script files with the extension in a folder named 'scripts' and whose location is defined in the program's settings. After a restart, a new menu entry appears and allows the execution of the installed scripts. Preprocessing + alignment + stacking can thus be fully automated. * Since version 0.9.9, it is also possible to launch Siril through the console and run a script without the

GUI The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...

. This can be useful when piloting a telescope remotely and only want to recover the pre-processed image. For example, entering the following command in a terminal runs the Processing.ssf script in the M31 images directory: siril -s ~/.siril/scripts/Traitememnt.ssf -d ~/Images/M31 *Version 0.9.10 allows commands to be sent through one named pipe while logs and status can be obtained through another. The mode is activated the command line argument -p.

Native file formats

FITS

Currently, Siril works internally with 32-bit

floating point images. Users can configure the program to work in

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16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mos ...

FITS format, in order to save computation time and disk space at the expense of image accuracy. Compression of FITS images is supported since version 0.99.4.

SER

The SER file format is a simple image sequence format, similar to uncompressed movies. Files in this format, widely preferred by astrophotographers in planetary imaging, do not need to be converted and can be edited on the fly.

Screenshot gallery

File:Gradient siril 0.9.12.png, Gradient removal File:Siril Exoplanet.png, Detecting an exoplanet using a light curve

References

{{Reflist Free astronomy software Astrophotography GNOME Applications Free software programmed in C Cross-platform free software Free software for BSD Free software for Linux Free software for Windows Free software for macOS Software using the GPL license