| Abstract : | Radio interferometers are designed to observe astronomical sources in the sky. During the low-frequency observation (< 1 GHz), they require a detailed calibration procedure to remove the effects of the ionosphere. Thus, the same calibration data can provide insight into the ionosphere. As upcoming radio telescopes become larger, ionospheric effects must be corrected to get a better image of the sky. Square Kilometer Array (SKA) pathfinder Giant Metrewave Radio Telescope (GMRT; lat∼19N) is located in geophysically sensitive regions between the magnetic equator, and the northern crest of the equatorial ionization anomaly is an excellent candidate to study ionosphere in various array configurations (centre square and arms antennas).
In our recent study, using the observation of a bright cosmic radio source with GMRT has demonstrated this telescope capability to detect variation in total electron content (TEC) with amplitudes ~1e-3 TECU and can measure TEC gradients with a precision of about 7e-4 TECU/Km. In this study, we introduce methods to perform spectral analyses on the computed TEC gradient, which was calculated using two different approaches. This method effectively tracks individual waves associated with medium scales travelling ionospheric disturbances (TIDs) and estimates the speed and directions of travelling ionospheric waves. |
