Representations of world coordinates in FITS
Open accessAbstract
The initial descriptions of the FITS format provided a simplified method for describing the physical coordinate values of the image pixels, but deliberately did not specify any of the detailed conventions required to convey the complexities of actual image coordinates. Building on conventions in wide use within astronomy, this paper proposes general extensions to the original methods for describing the world coordinates of FITS data. In subsequent papers, we apply these general conventions to the methods by which spherical coordinates may be projected onto a two-dimensional plane and to frequency/wavelength/velocity coordinates.
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Header sections store essential metadata as keyword/value pairs, including observational parameters, processing history, WCS information, and flux calibration.
“Critically, the header sections store essential metadata as keyword / value pairs. This includes observational parameters (telescope telemetry, instrument configuration, exposure time, filters), processing history (calibration steps, software versions), and arguably most importantly, the World Coordinate System (WCS) information (Greisen and Calabretta, 2002; Calabretta and Greisen, 2002) and flux”
From A high-throughput AES-GCM implementation on GPUs for secure, policy-based access to massive astronomical catalogs (2026) · cites this paper as Greisen and Calabretta, 2002
The Introduction describes FITS headers as keyword-equals-value records and says this paper defines WCS keywords. Section 5.4 gives an exposure-time keyword as an example. The cited paper does not establish the full list of header contents attributed to it, particularly processing history, software versions, and flux calibration. Page numbers are unavailable in our copy. (LLM, conf=0.88)
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Zur Elektrodynamik bewegter Körper
Einstein, A. (1905) · Annalen der Physik · doi:10.1002/andp.19053221004 · Cited by 4,385 · see citing works
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- Adobe Systems, Inc. 1999, PostScript Language Reference Manual, Third ed. (Addison-Wesley Publishing Company, Inc.), Reading, Massachusetts (see especially pages 293-296)
- McNally, D. (ed.) 1988, Transactions of the IAU, Proceedings of the Twentieth General Assembly (Dordrecht: Kluwer)
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Astropy: A community Python package for astronomy
The Astropy Collaboration, Robitaille, T. P., Tollerud, E. J., Greenfield, P., Droettboom, M., Bray, E., Aldcroft, T., Davis, M., Ginsburg, A., Price-Whelan, A. M., et al. (2013) · Astronomy & Astrophysics · doi:10.1051/0004-6361/201322068 · Cited by 14,620 · see citing works
Lemes-Perera, S., R. Alarcon, M., Caballero-Gil, P., & Serra-Ricart, M. (2026) · Astronomy and Computing · doi:10.1016/j.ascom.2026.101153 · Cited by 1 · see citing works
- Authors
- Greisen, E. W., & Calabretta, M. R.
- Affiliations
- National Radio Astronomy Observatory (US)
- Australia Telescope National Facility (AU)
- Venue
- Astronomy & Astrophysics
- Publisher
- EDP Sciences
- Published
- 2002-11-18
- Volume
- 395
- Issue
- 3
- Pages
- 1061-1075
- ISSN
- 0004-6361 (ISSN-L)
- 1432-0746
- OpenAlex
- W2051633863
- Cited by
- 206
- References
- 1
- Citations by year
- 2026: 11 · 2025: 8 · 2024: 12 · 2023: 12 · 2022: 16 · 2021: 7 · 2020: 12 · 2019: 6 · 2018: 8 · 2017: 12 · 2016: 18 · 2015: 13 · 2014: 11 · 2013: 6 · 2012: 8
- FWCI
- 7.34
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Astronomy and Astrophysics (publishedVersion)
- arXiv (Cornell University) (submittedVersion)
- arXiv (Cornell University)
- Funders
- National Aeronautics and Space Administration
- Space Telescope Science Institute
- Goddard Space Flight Center
- Topics
- Physical Sciences › Physics and Astronomy › Instrumentation › Astronomy and Astrophysical Research
- Physical Sciences › Engineering › Computational Mechanics › Astronomical Observations and Instrumentation
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Stellar, planetary, and galactic studies
- Keywords
- FITS format, world coordinates, coordinate systems, spherical projection
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