Exploring equatorial ionosphere using the GMRT
Abstract
In recent times, radio interferometers are not only used to observe astronomical sources but to study Earth's ionosphere with greater precision than any conventional ionospheric probes like the Global Navigation Satellite System (GNSS). Radio interferometers require a rough calibration procedure to remove the effects of the ionosphere, especially at low-frequency observation. Therefore, the same calibration data can be used to study the Earth's ionosphere. Pathfinder for Square Kilometer Array (SKA), Giant Metrewave Radio telescope (GMRT) is one of the largest sensitive radio telescopes operating at low-frequency regimes. The geographical location and configurations of the GMRT (centre square and arms antennas) make this telescope unique to explore the equatorial ionosphere region in different spatial scales.
Our study reveals by observing a bright radio source that the GMRT can measure ionospheric variation with a precision of about a few ∼ mTECU at 610 MHz, which is an order of magnitude more sensitive than current GNSS-based measurements. Spectral analysis of these observations tracks wave patterns associated with medium-scale travelling ionospheric disturbances (TIDs) and estimates the speed and direction of individual waves. This work will study the ionosphere at even lower radio frequencies and in different array configurations simultaneously. A similar study with upcoming instruments like SKA-LOW in Australia and SKA-MID in South Africa having different array configurations will probe the Earth's ionosphere and provide insight into various space weather phenomena.- Publication:
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44th COSPAR Scientific Assembly. Held 16-24 July
- Pub Date:
- July 2022
- Bibcode:
- 2022cosp...44..703M