Phase stability at low radio frequencies is severely impacted by ionospheric propagation delays. Radio interferometers such as the giant metrewave radio telescope (GMRT) are capable of detecting changes in the ionosphere’s total electron content (TEC) over larger spatial scales and with greater sensitivity compared to conventional tools like the global navigation satellite system (GNSS). Thanks to its unique design, featuring both a dense central array and long outer arms, and its strategic location, the GMRT is particularly well-suited for studying the sensitive ionospheric region located between the northern peak of the equatorial ionization anomaly (EIA) and the magnetic equator. In this study, we observe the bright flux calibrator 3C48 for ten hours to characterize and study the low-latitude ionosphere with the upgraded GMRT (uGMRT). We outline the methods used for wideband data reduction and processing to accurately measure differential TEC ($\delta \mathrm{TEC}$) between antenna pairs, achieving a precision of< mTECU (1 mTECU = ${10}^{-3}$ TECU) for central square antennas and approximately mTECU for arm antennas. The measured $\delta \mathrm{TEC}$ values are used to estimate the TEC gradient across GMRT arm antennas. We measure the ionospheric phase structure function and find a power-law slope of $\beta =1.72\pm 0.07$, indicating deviations from pure Kolmogorov turbulence. The inferred diffractive scale, the spatial separation over which the phase variance reaches $1{\mathrm{rad}}^2$, is ∼6.66 km. The small diffractive scale implies high phase variability across the field of view and reduced temporal coherence, which poses challenges for calibration and imaging.

We present a broadband spectropolarimetric analysis of the extragalactic radio source RACS_0900-28_7036 using Spectra and Polarization in Cutouts of Extragalactic Sources (SPICE-RACS) DR2 observations with the Australian Square Kilometre Array Pathfinder (ASKAP). The source was selected for its large rotation measure (RM = 345.7 ± 0.2 rad m ⁻² ), substantial excess relative to the local foreground (ΔRM ≈ 171 rad m ⁻² ), and strong evidence of Faraday complexity ( σ _add / δσ _add ≈ 8.6). Observations span 803–1083 MHz in 36 spectral channels, enabling detailed characterization of Faraday rotation and wavelength-dependent depolarization. One-dimensional QU fitting and Bayesian model selection identify a multicomponent model comprising one Burn-slab component and two external Faraday dispersion (EFD) components (1 Slab + 2 EFDs) as the preferred description. The dominant astrophysical component exhibits RM ≈ 345.5 rad m ⁻² with modest Faraday dispersion ( σ _RM ≈ 3 rad m ⁻² ), consistent with the Galactic foreground RM at the source position (RM _Gal = 331.9 ± 33.1 rad m ⁻² ). A secondary broader component at RM ≈ 131.5 rad m ⁻² shows strong depolarization ( σ _RM ≈ 19.5 rad m ⁻² ), indicating an additional turbulent Faraday-active medium along the line of sight. The fractional polarization spectrum and q – u plane evolution further confirm multiple Faraday-active regions along the line of sight. These results demonstrate that ASKAP broadband spectropolarimetry can resolve complex Faraday structures and probe turbulent magnetized environments, providing a framework for systematic depolarization studies across the full SPICE-RACS catalog and enabling statistical investigations of Faraday complexity in diverse extragalactic radio sources.

Phase stability at low radio frequencies is severely impacted by ionospheric propagation delays. Radio interferometers such as the Giant Metrewave Radio Telescope (GMRT) are capable of detecting changes in the ionosphere's total electron content (TEC) over larger spatial scales and with greater sensitivity compared to conventional tools like the Global Navigation Satellite System (GNSS). Thanks to its unique design featuring both a dense central array and long outer arms-and its strategic location, the GMRT is particularly well-suited for studying the sensitive ionospheric region located between the northern peak of the Equatorial Ionization Anomaly (EIA) and the magnetic equator. In this study, we observe the bright flux calibrator 3C48 for ten hours to characterize and study the low-latitude ionosphere with the upgraded GMRT (uGMRT). We outline the methods used for wideband data reduction and processing to accurately measure differential TEC (dTEC) between antenna pairs, achieving a precision of less than 1 mTECU for the central square antennas and approximately 1 mTECU for the arm antennas. The measured dTEC values are used to estimate the TEC gradient across the GMRT arm antennas. We measure the ionospheric phase structure function and find a power-law slope of $β= 1.72$, indicating deviations from pure Kolmogorov turbulence. The inferred diffractive scale the spatial separation over which the phase variance reaches $1 \text{rad}^2$ is 6.66 km. A small diffractive scale implies high phase variability across the field of view and reduced temporal coherence, which poses challenges for calibration and imaging.