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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 observations of the highly active FRB20201124A with the upgraded Giant Metrewave Radio Telescope (uGMRT) at 550–750 MHz. These observations in the incoherent array mode simultaneously provided an arcsecond localization of bursts from FRB20201124A, the discovery of persistent radio emission associated with the host galaxy, and the detection of 48 bursts. Using the brightest burst in the sample (F  = 108 Jy ms), we find a structure-maximizing dispersion measure of 410.8 ± 0.5 pc cm−3. We find that our observations are complete down to a fluence level of 10 Jy ms, above which the cumulative burst rate scales as a power law |$R(\gt \!F) = 10~{\rm h}^{-1} \left(F/10\mathrm{\, Jy\, ms}\right)^{\gamma }$|⁠ , with γ  = −1.2 ± 0.2. We find that the bursts are, on average, wider than those reported for other repeating fast radio bursts (FRBs). We find that the waiting time between bursts is well approximated by an exponential distribution with a mean of ∼2.9 min during our observations. We searched for periodicities using both a standard Fourier domain method and the fast folding algorithm, but found no significant candidates. We measure bulk spectro-temporal drift rates between −0.75 and −20 MHz ms−1. Finally, we use the brightest burst to set an upper limit to the scattering time of 11.1 ms at 550 MHz. The localization of FRB20201124A adds strength to the proof-of-concept method described in our earlier work and serves as a potential model for future localizations and follow-up of repeating FRBs with the uGMRT. [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]

This document is a correction notice for an article titled "Modelling Annual Scintillation Velocity Variations of FRB 20201124A" published in the Monthly Notices of the Royal Astronomical Society: Letters. The correction addresses a typo in the published abstract, where "pc" should be replaced by "kpc." The corrected abstract discusses the measurement of scintillation velocity at 10 epochs over a year, indicating that the screen is within the Milky Way. The modeling of the annual variation suggests a screen distance of 0.40±0.04 kpc or 0.46±0.06 kpc from Earth, potentially associated with material outside of the Local Bubble or the edge of the Orion-Eridanus Superbubble. The authors of the article are R A Main, S Bethapudi, V R Marthi, M L Bause, D Z Li, H-H Lin, L G Spitler, and R S Wharton. [Extracted from the article]

The purpose of this paper is to develop a patient-specific dose estimation system in nuclear medicine examination. A dose deposition routine to store the deposited energy of the photons during their flights was embedded in the widely used SimSET Monte Carlo code and a user-friendly interface for reading PET and CT images was developed. Dose calculated on ORNL phantom was used to validate the accuracy of this system. The ratios of S value for 99mTc, 18F and 131I computed by this system to those obtained with OLINDA for various organs were ranged from 0.93 to 1.18, which were comparable to that obtained from MCNPX2.6 code (0.88–1.22). Our system developed provides opportunity for tumor dose estimation which cannot be known from the MIRD. The radiation dose can provide useful information in the amount of radioisotopes to be administered in radioimmunotherapy. [ABSTRACT FROM AUTHOR]