A Comparative Study-of Equatorial Radio Source Scintillations & the Scintillations Expected for ATS-6 Emissions over India

Abstract

The large radio telescope system at Ootacamund near the geomagnetic equator is used with advantage to study the ionospheric scintillations in the equatorial belt. Several narrow diameter radio sources were observed with the above system and some preliminary scintillation results at 327 MHz are reported. The scintillation indices derived from the actual records are compared with the existing Fremouw & Rino global model. The model grossly underestimates the scintillation indices by as much as one order of magnitude at low solar activity levels. Various possible reasons for the inadequacy of the above said model are discussed. Further, in view of the Indian SITE programme on 860MHz from the ATS-6 satellite, the expected scintillation indices based on Fremouw & Rino model at various centres in India are calculated. However, due to the inherent discrepancy in the calculation of the values for radio source scintillations from the above model, these expected scintillation indices for the SITE programme should be viewed with caution.