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Hubble Space Telescope
FOC Reseau Positions

The six text files listed here contain the X and Y pixel coordinates of reseau marks. There are four files for the f/96 relay and two for f/48 available:

The file name begins with "f48" or "f96" for the relay name and is followed by a four-letter code for the image format. The code "zlrg" refers to the full photocathode, 512 zoom by 1024. (The reseau positions are for a dezoomed image, 1024 by 1024.) The code "n512" refers to the 512 by 512 centered format. The extension "geo" or "raw" indicates whether the reseau positions are for geometrically corrected images or non-corrected. Each file contains a couple of header lines beginning with the "#" sign, which is meant to be interpreted as a comment character. The rest of the file consists of two columns of numbers, the X and Y pixel coordinates of the reseau positions. In most cases the numbers are given to 0.1 pixel, but remember that the geometric distortion varies with time, so these positions will not be accurate to 0.1 pixel for every image. There are four additional fiducial marks on the photocathode, and their positions are also included. All four of these marks are within the 1024 by 1024 format, but only one is within the 512 by 512 format.