Detection of large scale electron density irregularities duringips observations at 103 MHz

Angular displacements in the positions of the quasar 3C 298 were observed during its interplanetary scintillation (ips) observations made using a correlation interferometer at 103 MHz at Thaltej near Ahmedabad. These changes in the apparent positions of the source could be seen as variations in the declination of 3C 298. Two possibilities which might cause such effects are considered; refraction of the radio waves either in the earth’s ionosphere or in the interplanetary medium (ipm) by large scale plasma density inhomogeneities. Order of magnitude calculations for both are presented. Further studies using two-site observations are suggested to decide between the two mechanisms.