SIMBAD references

We present galactic maps of the distribution of neutral sodium absorption column density using the newly determined Hipparcos satellite distances for a total of 290 stars lying within 250pc of the Sun. These maps now replace those originally presented in Welsh et al. (1994ApJ...437..638W). The Local Bubble is now seen to be a neutral gas-free cavity (n_H<0.01cm^–3) with a radius of at least 70pc in most directions, more than 50% larger in volume than previously determined from NaI absorption data. Additionally, the well-known low-density interstellar tunnel in the direction of the star β CMa is almost twice as wide as previously thought, and the existence of a similarly tenuous interstellar feature has been identified in the galactic direction of Lupus-Norma extending to at least 170pc. Finally, we note the absence of dense neutral gas out to a distance of at least 100pc in the direction of galactic longitude l^II=135°.