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Compact radio sources exhibit scintillation, an interference pattern arising from propagation through inhomogeneous plasma, where scintillation patterns encode the relative distances and velocities of the source, scattering material, and Earth. In previous work, we showed that the scintillation velocity of the repeating fast radio burst (FRB) FRB20201124A could be measured by correlating burst spectrum pairs, with low values of the scintillation velocity and scattering time-scale suggesting scattering nearby the Earth at $\sim$ 0.4 kpc. In this work, we have measured the scintillation velocity at 10 epochs spanning 1 yr, observing an annual variation that strongly implies the screen is within the Milky Way. Modelling the annual variation with a 1D anisotropic or 2D isotropic screen results in a screen distance $d_{\mathrm{ l}} = 0.40\pm 0.04$ or $0.46\pm 0.06\,$ pc from the Earth, respectively, possibly associated with material outside of the Local Bubble or the edge of the Orion–Eridanus superbubble. Additional measurements particularly at times of low effective velocity will help probe changes in screen properties, and distinguish between screen models. Where scintillation of an FRB originates in its host galaxy or local environment, these techniques could be used to detect orbital motion, and probe the FRB's local ionized environment. [ABSTRACT FROM AUTHOR]

We report the findings of an upgraded Giant Metrewave Radio Telescope (uGMRT) observing campaign for FRB 180916.J0158+65, which was recently found to show a 16.35-d periodicity of its active cycle. We observed the source at 550–750 MHz for ∼2 h during each of three successive cycles at the peak of its expected active period. We find 0, 12 and 3 bursts, respectively, implying a highly variable bursting rate even within the active phase. We consistently detect faint bursts with spectral energies only an order of magnitude higher than the Galactic burst source SGR 1935+2154. The times of arrival of the detected bursts rule out many possible aliased solutions, strengthening the findings of the 16.35-d periodicity. A periodicity search over a short time-scale returned no highly significant candidates. Two of the beamformer-detected bursts were bright enough to be clearly detected in the imaging data, achieving subarcsec localization, and proving to be a proof-of-concept for FRB imaging with the GMRT. We provide a 3σ upper limit of the persistent radio flux density at 650 MHz of 66 μJy, which, combined with the European VLBI Network and Very Large Array limits at 1.6 GHz, further constrains any potential radio counterpart. These results demonstrate the power of the uGMRT for providing targeted observations to detect and localize known repeating FRBs. [ABSTRACT FROM AUTHOR]