Exploring data combination techniques for interferometric and single-dish observations in the ALMA era

Interferometric observations are often utilized to attain high angular resolution, but in many astronomical scenarios it is critical to also recover extended emission. Combining interferometric and single dish observations is a viable option to overcome the so-called “short spacing problem” and recover flux that would otherwise be missing in interferometry-only images. But how does one know whether all, or most, flux is truly recovered across all scales? As part of a community-driven effort gathering teams and expertise from different ALMA partners, we aim to explore current interferometric combination techniques in a consistent manner and assess their relative merit. We generate synthetic observations of standard ISM conditions probing a wide range of spatial scales: molecular clouds whose emission follows a power law, and a point source within an extended Gaussian. In this poster, we present combinations using techniques from common software packages (especially CASA) and the literature: sdintimaging, feather, model-assisted clean, tp2vis, and combination in the image domain. Our team has developed several image assessment methods, allowing us to quantitatively compare the output images. While our aim is data combination, some of the assessments should be applicable for ancillary imaging and analysis, including but not limited to interferometric and single dish images. The outcome of this effort is a manuscript with fully reproducible images generated with publicly available data, a combination module for Python, and a script repository.