Filter-Dependent Sky Flats for WFC3/IR

We present filter-dependent sky flats for Hubble’s WFC3/IR detector, computed by stacking observations of sparse fields (with sources masked) over the instrument lifetime. The new flats replace the current set of P-flat reference files, which were based on ground test data with a single ‘grey’ correction for all filters derived from early inflight data. The sky flats correct for wavelength-dependent residuals ~1% at the center of the detector and ~2% at the detector edges with Poisson errors of 0.2% or better. We also present ‘delta’ flat corrections in six filters for all known ‘blobs’ by stacking observations before and after their individual appearance dates, and these correct for sensitivity residuals of ~5–10%.