Searching for IDV in the quasar B2005+403

K.E. Gabanyi, T.P. Krichbaum, U. Bach, A. Witzel and J.A. Zensus (MPIfR)

B2005+403 is a z=1.74 quasar located in the direction of Cygnus (65<l<90
|b|<10). At long wavelengths (6, 13 and 18 cm), pronounced interstellar
scattering affects the source image. Previous VLBI measurements by Desai
& Fey, Fey  et al. indicate strong angular broadening at long
wavelengths.
With the Effelsberg 100 m radio Telescope, we performed a
single dish, 12-hour flux density monitoring in November 2003
at 18 and 6 cm to determine whether B2005+403 (and the other sources in
Fey et al.'s angular broadening measurement) shows intraday
variability. In my talk I will present the results from this measurement
and a statistical analysis.
In order to study the internal source structure,  VLBI
observations have to be performed at short wavelengths, where
scattering is not important. We show new maps at 15, 22, and 43 GHz
and discuss these in the context of ISS and structural  variability.