RADIO STAR AND SATELLITE SIGNAL SCINTILLATION BY E-REGION IRREGULARITIES - A CASE-STUDY

Here we present the study of daytime scintillation due to E region irr egularities at low latitudes from a set of simultaneous observations o n June 3, 1993. The effects of these irregularities are clearly seen o n (1) the 103 MHz signal of the radio star 3C 196 recorded at Rajkot a nd at Thaltej (near Ahmedabad, India), (2) the 244-MHz radio beacon of Fleetsat satellite (73-degrees-E) recorded at Ahmedabad, and (3) the ionosonde being operated at Ahmedabad. These observations provide an e stimate of the irregularity patch with a spatial extent of around 400 km east-west and 80 km north-south. As the subionospheric points of th e radio source and satellite observations are quite far apart, a study on the dynamics of these irregularities is also possible which indica tes a southward movement of the patch. The drift speed of approximatel y 60 m/sec is calculated from the upper frequency roll off of the scin tillation spectrum at 103 MHz. This is found to be consistent with ear lier investigations of blanketing Es near magnetic equator.