WSRT AND VLA OBSERVATIONS OF HI IN THE DIRECTION OF 3C-10

Westerbork Synthesis Radio Telescope HI observations combined with Eff elsberg 100 m antenna observations have been made of the galactic supe rnova remnant 3C 10 (Tycho) with an angular resolution similar or equa l to 50 '' and a velocity resolution of 0.62 km s(-1) and with the VLA with resolutions of similar to 13 '' and 1.3 km s(-1), respectively. HI absorption against 3C 10 was detected in the velocity range -60 les s than or equal to v less than or equal to 10 km s(-1). The most negat ive velocity component is at -57 km s(-1). HI absorption in the direct ion of extragalactic source 3C11.1 and two additional sources close to 3C 10 (distance less than or similar to 1 degrees) was obtained using the Very Large Array. Comparison of the spectra together with two oth er sources from Taylor and Roberts (1993) (distance less than or simil ar to 2 degrees) leads to the conclusion that 3C 10 is at a distance o f 4.5 kpc. The implications of this distance are discussed. The HI abs orption at -48 km s(-1) in the direction of 3C 10 shows a filament of size similar to 4'. Self-absorption near 3C 10 is also detected at thi s velocity, and an upper limit of 25 K for the spin temperature can be derived. A comparison with a high resolution 100 mu. IRAS image is di scussed. The HI absorption at low velocities (-20 less than or equal t o v less than or equal to +10 km s(-1)) shows primarily large scale st ructure. For this gas a spin temperature of 75 K can be derived. All d istances are based on R. = 8.5 kpc.