STScI Logo

Hubble Space Telescope
[08/24/2010] Image Distortion Polynomials for WFC3 IR Filters (Second 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NOTE: As of October 11, 2010, this file has been superseded by a newer version available from CDBS.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 Image Distortion Table (IDCTAB) released here, ir_240810_idc.fits, contains unique polynomial function coefficients from calibrations of five IR filters (F098M, F110W, F125W, F139M, and F160W). For all other filters in this IDCTAB, the values of the polynomial coefficient are those of the F160W polynomials. Image shifts between filters (e.g., few tenths of a pixel shifts caused by filter wedge) are not calibrated in this release. The coefficients in this new calibration are slightly rotated (<0.01 deg) with respect to the previous, five-filter alpha release (5-20-2010). The measured rotation between these IR filter polynomials is less than 0.0005 deg (i.e., 0.1 pixel). The measured rotation between the IR polynomials and the UVIS filter distortion polynomials of the preceding alpha release (7/26/2010) is less than 0.01 deg. With this calibration, displacements between rectified images less than 0.12 pixel (0.08 pixel r.m.s.) can be obtained with MultiDrizzle and a user-determined shift file that represents differential shift, magnification, and rotation between exposures (e.g., using values determined with the STSDAS task tweakshifts.) The IR IDCTAB is described in WFC3 ISR 2009-34, "WFC3 SMOV Proposal 11445 - IR Geomeric Distortion Calibration," Kozhurina-Platais, et al.

Created 08/24/10 MJD
Modified 10/11/2010 MJD