VSOP observations of a GHZ-peaked spectrum source OQ 208 Original Research Article

We present λ18 cm VSOP observations towards a GHz-peaked spectrum (GPS) source OQ 208. A double lobe seen by high-frequency ground VLBI observations is confirmed, although its brightness is more asymmetric at lower frequency. Comparing with images at higher frequency, we found asymmetric free-free absorption towards the double lobe. We can explain the spectral asymmetry by a slant jet axis against line of sight, which causes different optical depth in the ambient plasma.