Astrometry and photometry with HST-WFC3. I. Geometric distortion corrections of F225W, F275W, F336W bands of the UVIS-channel

TL;DR

This paper develops a geometric distortion correction for HST's UVIS-channel in specific UV filters, enabling high-precision astrometry with approximately 1 milliarcsecond accuracy, crucial for advanced astronomical measurements.

Contribution

It provides the first average correction for geometric distortion in the UVIS-channel of HST's WFC3 for three UV filters, improving astrometric precision.

Findings

Achieved ~1 mas relative astrometric accuracy in UV filters

Provided a first average geometric distortion correction for UVIS-channel

Identified need for further data to refine the correction

Abstract

An accurate geometric distortion solution for the Hubble Space Telescope UVIS-channel of Wide Field Camera 3 is the first step towards its use for high precision astrometry. In this work we present an average correction that enables a relative astrometric accuracy of ~1 mas (in each axis for well exposed stars) in three broad-band ultraviolet filters (F225W, F275W, and F336W). More data and a better understanding of the instrument are required to constrain the solution to a higher level of accuracy.