SIMBAD references

New observations of the colliding wind Wolf-Rayet WC7+O4-5 binary HD 193793 (WR 140) at 6cm and 21cm with the Westerbork Synthesis Radio Telescope are presented. They show that the 21cm flux, in particular, rose to a sharp maximum in 1992, lagging about a year behind the 6cm flux. After maximum, both fell simultaneously. The data are interpreted in terms of the varying circumstellar extinction to a non-thermal source where the WC and O winds collide. The rising branch of the flux curve is determined mostly by extinction in the WC stellar wind and the fading branch mostly by that in the O star wind.