Multi-Frequency Study of FRB20201124A with the uGMRT

We present results from a monitoring campaign of FRB 20201124A using the uGMRT during its active phase between MJD 59342 and 59362. Simultaneous observations in Band 4 (550-950 MHz) and Band 5 (1060-1460 MHz) provide a uniform view of the source activity. The burst activity exhibits a frequency-dependent evolution, with the last Band-5 burst detected on MJD 59358, while Band-4 activity persisted until MJD 59362. We identified burst pairs in the simultaneously observed Band-4 and Band-5 data, with time separations of 31.8 ms and 52.3 ms. These separations are comparable to the short-timescale component of the waiting-time distribution, which peaks at about 60 ms, suggesting that the multi-band burst pairs may be associated with the same short-timescale clustering process. Contemporaneous FAST observations detected the Band-5 bursts but revealed no strictly simultaneous counterparts to the corresponding Band-4 bursts. These results suggest frequency-dependent burst occurrence and are consistent with patchy spectral occupancy over the 550--1460 MHz frequency range. The detected bursts exhibit diverse temporal and spectral morphologies. Consecutive bursts were observed with separations of 16.7(2)-291.5(6) ms, revealing short repetition intervals and possible sub-second quasi-periodicity. The waiting-time and energy distributions are bimodal, indicating at least two characteristic emission timescales and energy modes. Burst fluences span 1.7(3)-78(3) Jy ms, and the cumulative fluence distribution is well described by a broken power law. These results provide a simultaneous multi-frequency view of FRB 20201124A during its May 2021 active episode and support a picture in which the source exhibits complex frequency-dependent activity and broadband emission behaviour.