A search for intergalactic HI gas in the NGC 1808 group of galaxies

A mosaic of six H I line observations with the Australia Telescope Compact Array is used to search for intergalactic gas in the NGC1808 group of galax ies. Within the field of view of about 1.degrees4 x 1.degrees2 no emission from intergalactic H I gas is detected, either in the form of tidal plumes or tails, intergalactic HI clouds, or as gas associated with tidal dwarf ga laxies, with a 5 sigma limiting sensitivity of about 3 x 10(18) cm(-2) (or 1.4 x 10(7) M-. at a distance of 10.9 Mpc, for the given beam size of 127." 9 x 77."3). The H I data of NGC1792 and NGC1808, with a velocity resolution of 6.6 km s(-1), confirm the results of earlier VLA observations. Simultan eous wide-band 1.34 GHz continuum observations also corroborate the results of earlier studies. However, the continuum flux of NGC1808 measured by us is almost 20% higher than reported previously. No radio continuum emission was detected from the type Ia supernova SN1993af in the north-eastern spira l arm of NGC1808. A comparison of NGC1792 and NGC1808 shows that it is not primarily the total energy input that makes the big difference between the starburst-related out ow in NGC1808 and the absence of such extraplanar fea tures in NGC1792, but the area over which the energy released by stellar wi nds and supernovae is injected into the ISM.