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[06/04/2010] Image Distortion Polynomials for WFC3 UVIS Filters (Alpha Release)

NOTE: As of October 11, 2010, this file has been superseded by a newer version available from CDBS. More details are available here.

The geometric distortion of WFC3 images in the UVIS channel is represented by a 4th order general polynomial, as described in WFC3 ISR-2009-33. For each filter, unique coefficient values are stored in the Image Distortion Correction Table (IDCTAB). However, the first release of the IDCTAB contains the same set of coefficient values for each filter, which were determined from images in the F606W filter. Although the differences in filter-to-filter distortion are small, they are not negligible. Therefore, we present here an IDCTAB containing distinct, newly determined coefficient values for three UVIS filters: F225W, F275W, and F336W. The coefficients for these three filters are derived from nine exposures of Omega Cen in each filter, taken with a large dither pattern in July 2009. The coefficients for the other UVIS filters (including F606W) remain those previously determined from images of 47 Tuc in the F606W filter.

This distribution (t20100603_uvis_idc.fits) is an alpha release of the UVIS IDCTAB, which we intend to install in CDBS and the OPUS pipeline by mid-June, 2010. Please notify help@stsci.edu of any discrepancies in the application of this calibration data.

Created 06/04/2010 MJD
Modified 10/11/2010 MJD