Hi observations of three compact high-velocity clouds around the

ABSTRACT Context. We present deep Hi observations of three compact high-velocity clouds (CHVCs).Aims. The main goal is to study their di use warm gas and compact cold cores. We use both low- and high-resolution data obtainedwith the 100 m E elsberg telescope and the Westerbork Synthesis Radio Telescope (WSRT). The combination is essential in orderto study the morphological properties of the clouds since the single-dish telescope lacks a sucient angular resolution while theinterferometer misses a large portion of the di use gas.Methods. Here single-dish and interferometer data are combined in the image domain with a new combination pipeline. The combi-nation makes it possible to examine interactions between the clouds and their surrounding environment in great detail.Results. The apparent di erence between single-dish and radio interferometer total flux densities shows that the CHVCs contain aconsiderable amount of di use gas with low brightness temperatures. A Gaussian decomposition indicates that the clouds consistpredominantly of warm gas.