Astrometry and photometry with HST WFC3. II. Improved geometric-distortion corrections for 10 filters of the UVIS channel

TL;DR

This paper provides an improved geometric-distortion correction for HST UVIS channel across ten filters, enhancing astrometric and photometric accuracy with a detailed polynomial and residual correction approach.

Contribution

The paper introduces a new, precise distortion correction method for HST UVIS data, combining polynomial modeling and residual tables for ten filters, improving accuracy over previous solutions.

Findings

Final correction accuracy better than 0.008 pixels (~0.3 mas)

Provides correction tools in FORTRAN and FITS formats

Enhances astrometric and photometric measurements for UVIS data

Abstract

We present an improved geometric-distortion solution for the Hubble Space Telescope UVIS channel of Wide Field Camera 3 for ten broad-band filters. The solution is made up of three parts: (1) a 3rd-order polynomial to deal with the general optical distortion, (2) a table of residuals that accounts for both chip-related anomalies and fine-structure introduced by the filter, and (3) a linear transformation to put the two chips into a convenient master frame. The final correction is better than 0.008 pixel (~0.3 mas) in each coordinate. We provide the solution in two different forms: a FORTRAN subroutine and a set of fits files, one for each filter/chip/coordinate.