The evolution of stars between the AGB and planetary nebula phases was investigated by sensitive radio continuum observations of a sample of 21 evolved stars with high mass loss rates and extended circumstellar envelopes, in a search for newly formed compa

7 cases these positions di er signi cantly. Wright et al. (1990) nd an o set of more than 100 between the optical and SiO maser positions for VY CMa, which they attribute to structure in the dusty circumstellar shell. We use the SiO maser position. Precise position measurements of IRC+10011 have been made at both optical and radio wavelengths. Optical measurements by Costa and Loyola (1990) and Xu et al. (1991) give (1950)= 01h 03m 52:4s; (1950)=+12o 200 2000 . Radio interferometric measurements of the OH 1612 MHz line by Bowers, Johnston and Spencer (1983) and of the SiO thermal emission by Lucas et al. (1992), on the other hand, nd (1950)= 01h 03m 48:1s; (1950)=+12h 190 5100 . The IRAS position (IRAS Science Working Group 1988) agrees with that given by the radio lines. IRC+10011 may be faint at optical wavelengths and the optical measurements may be of a nearby unrelated star. We use the radio position in

the present paper.

3. OBSERVATIONS AND RESULTSThe data were obtained with 27 antennas of the NRAO1 Very Large Array in The National Radio Astronomy Observatory is operated by Associated Universities Inc. under cooperative agreement with the National Science Foundation. its\C" con guration during 1991 January 2 and 27. Both right and left circularly polarized modes were observed with 50 MHz bandpasses centered respectively at 8414.9 and 8464.9 MHz. The integration times ranged from 30 to 60 minutes per source. The phases were calibrated by observations of nearby bright point sources. The ux density scale was calibrated by an observation of 3C286 (1328+307), for which the adopted ux density at 3.6 cm was 5.27 Jy. The data were calibrated and analyzed with the NRAO AIPS data reduction package.1