TNX Convention for Representing FITS Image Distortions
The 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.
September 2008 by Doug Tody (NRAO), Lindsey
Davis (NOAO), and Frank Valdes (NOAO)
Date and Place of First Usage:
circa 1998 for NOAO data and support within the IRAF system.
Extent of Usage:
The TNX convention is currently used in the FITS files
produced by NOAO that are taken with a variety of different
imaging instruments including MOSAIC and NEWFIRM.
Comments and/or critiques:
Sample FITS File:
Sample Header Listing:
tnx.txt (edited to show only the relevant keywords)
Last revised: Wednesday, 12-May-2010 14:16:09 EDT
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