The interaction of the supernova remnant VRO 42.05.01 with its HI environment

H I observations of a 20.13 field centred on the SNR VRO 42.05.01 (G166.0 + 4.3) are presented with resolution of 2 km s-1 in velocity and 4 arcmin in angle. Full sensitivity to structures of all angular sizes down to this scale is ensured by combining single-antenna and aperture synthesis telescope data. The interaction of the SNR with the surrounding H I is seen. The observations support a previous model developed to explain the unusual structure of the SNR; after initial expansion in a warm medium of density ∼ 1 cm-3 the blast wave has broken into and re-energized a pre-existing low-density (∼ 0.01 cm-3) hot cavity. Despite confusion with extraneous H I, features clearly related to the SNR can be seen. (author)