1ST 43 GHZ VLBI-OBSERVATIONS WITH THE 30-M RADIO TELESCOPE AT PICO-VELETA

A three station VLBI experiment performed at 43 GHz (lambda = 7 mm wavelength) demonstrated the superior performance of the 30-m millimeter radio telescope of IRAM at Pico Veleta especially for mm-VLBI observations. Although primarily intended as a technical test, these first 43 GHz VLBI observations with Pico Veleta yielded new scientific results. A first VLBI map of Cygnus A (= 3C 405) at 43 GHz shows a core-jet-like structure of approximately 4 mas length, with several compact components embedded. The map also shows some evidence for jet bending near the core of about DELTAP.A. = 5-15-degrees. The apparent subluminal motion in the ''inner jet'' of 3C 84 (= NGC 1275) is confirmed and seems to show (apparent) acceleration along the jet from 21 000 km s-1 close to the nucleus to 11 4 000 km s-1 at approximately 4 mas separation from the VLBI-core. The absence of any detectable counter-jet requires either a direct orientation of the jet towards the observer or a pronounced asymmetry between jet and counter-jet. In 3C 345 the apparent superluminal motion along bent trajectories of two recently ejected jet components (C6 and C7) was further monitored. Inspection of their paths indicates trajectories largely different from each other and from those of their precursors. These results and the detection of other extragalactic objects and galactic SiO-maser sources show that the participation of the IRAM 30-m radio telescope in VLBI observations at millimeter wavelengths greatly enhances the detection threshold and imaging capabilities of mm VLBI.