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Precision Effects for Solar Image Coordinates Within the FITS World Coordinate SystemThe FITS world coordinate system (WCS) provides a number of tools for precisely specifying the spatial coordinates of an image. Many of the finer details that the WCS addresses have not historically been taken into account in solar image processing. This paper examines various effects which can affect the expression of coordinates in FITS headers, to determine under what conditions such effects need to be taken into account in data analysis, and under what conditions they can be safely ignored. Effects which are examined include perspective, parallax, spherical projection, optical axis determination, speed-of-light effects, stellar aberration, gravitational deflection, and scattering and refraction at radio wavelengths. Purely instrumental effects, such as misalignment or untreated optical aberrations, are not considered. Since the value of the solar radius is an experimental quantity, the effect of adopting a specific radius value is also examined. These effects are examined in the context of a previous paper outlining a WCS standard for encoding solar coordinates in FITS files. Aspects of that previous paper are clarified and extended in the present work.
Document ID
20110013557
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Thompson, W. T.
(ADNET Systems, Inc. MD, United States)
Date Acquired
August 25, 2013
Publication Date
March 12, 2010
Publication Information
Publication: Journal of Astronomy and Astrophysics
Volume: 515
Subject Category
Solar Physics
Report/Patent Number
GSFC.JA.4632.2011
Funding Number(s)
CONTRACT_GRANT: NNG06EB68C
Distribution Limits
Public
Copyright
Other

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