See also the local FITS conventions , the registered extension names, and keyword dictionaries.
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The Registry of FITS Conventions
Maintained by the IAU FITS Working Group
The Registry of FITS Conventions provides a central and authoritative repository for documenting conventions that have been developed by the FITS user community for storing and transmitting various types of information in FITS format data files. A FITS convention is defined as a set of related FITS header keywords, and optionally, other data structures within FITS tables, FITS images, or other types of conforming FITS extensions that are to be used for a specific purpose. The IAU FITS Working Group is responsible for the this Registry and for the rules and procedures for entering new conventions into it.
These conventions are not necessarily recommended by the IAU FITS Working Group for reuse in new applications. The registration process is mainly designed to ensure that the documentation about the existing FITS convention meets a minimum level of completeness and clarity. A separate and more rigorous review process is required before a FITS convention is endorsed by the IAUFWG and is approved as part of the FITS Standard.
Registered Conventions:
Conventions that have been reviewed and incorporated into the FITS Standard:
The following 6 conventions were reviewed by the IAU FITS Working Group in 2016 and have been officially incorporated into version 4.0 of the FITS Standard. The documentation about these conventions provided here may contains additional details than is given in the FITS Standard, but in case of any descrepancies, the specifications in the Standard shall supersede what is given here.
- Header space convention for pre-allocating space for additional header keywords that will be written later.
- CONTINUE Long String Keyword convention for writing string keyword values that are longer than the 68-character limit of a single FITS keyword.
- Column Limits keywords (TLMINn/TLMAXn & TDMINn/TDMAXn).
- CHECKSUM keyword convention for verifying the integrity of FITS HDUs.
- Tiled Image Compression divides image into a grid of tiles, and stores the compressed tiles in a variable length array column of a binary table.
- Tiled Table Compression convention for compressing FITS binary tables, analogous to the tiled image compression convention.
General Conventions:
- Green Bank Keyword convention for recording parameters related to images that are stored in a vector column of a FITS binary table.
- INHERIT keyword indicates that a HDU should inherit the primary header keywords.
- ESO HIERARCH Keyword convention uses a hierarchical structure to define the keyword name. This convention can be generalized to support keyword names longer than 8 characters or containing characters that would not be allowed in a standard FITS keyword name.
- Substring Array Convention for Binary Tables may be used to specify that a character array field (TFORMn = 'rA') consists of an array of either fixed-length or variable-length substrings within the field.
- Hierarchical Grouping for defining hierarchical associations of HDUs.
- FOREIGN file encapsulation for wrapping other types of files in FITS.
World Coordinate Systems Conventions:
- Spatial Region File convention defines a spatial region within a 2-dimensional image.. The region is specified as the union or intersection of geometric shapes, such as 'circle' or 'rectangle'. The region file is often used to define an area that is to be included or excluded from certain data processing operations on the image
- Simple Imaging Polynomial convention provides a convenient means of representing non-linear geometric distortion of the coordinate system as polynomials in FITS header keywords.
- TNX World Coordinate System is a non-standard coordinate system for evaluating celestial coordinates from the image pixel coordinates. It follows the FITS conventions for undistorted tangent plane projections but adds a non-linear distortion term to the evaluation.
- TPV World Coordinate System is a non-standard convention that builds on the standard TAN projection by adding a general polynomial distortion correction.
- ZPX World Coordinate System is a non-standard convention that builds on the standard ZPN projection by adding a general polynomial distortion correction.
Conventions applicable to specific types of data:
- FITS Interferometry Data Interchange (FITS-IDI) Convention for the interchange of data recorded by interferometric telescopes, particularly at radio frequencies and very long baselines.
- SDFITS binary table convention for interchange of single dish data in radio astronomy.
- Multi-Beam FITS (MBFITS) data format for single-dish millimeter and sub-millimeter telescopes.
- Euro3D: An interchange data format for integral field spectroscopy in which 1-dimensional spectra are obtained at multiple positions over a 2-dimensional spatial field of view.
- OIFITS: A Data Standard for Optical Interferometry.
- PSRFITS - a Standard for Pulsar Data Storage.
- Photographic Plates - a Standard for Header Keyword in Scans of Sky Images on Photographic Plates.
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