Detection of band-limited bursts from highly active FRB 20240114A by FAST

ATel #16433; Junshuo Zhang(NAOC), Yuhao Zhu(NAOC), Shuo Cao(YNAO), Dejiang Zhou(NAOC), Yongkun Zhang(NAOC), Jintao Xie(Zhejiang Lab), Qin Wu(NJU), Tiancong Wang(BNU), Pei Wang(NAOC), Chenhui Niu(CCNU), Di Li(NAOC), Weiwei Zhu(NAOC), Bing Zhang(UNLV), Jinlin Han(NAOC), Kejia Lee(PKU & NAOC), Fayin Wang(NJU), He Gao(BNU), Yi Feng(Zhejiang Lab), Jinchen Jiang(NAOC), Weicong Jing(NAOC), Ye Li(PMO), Wanjin Lu (NAOC), Rui Luo (GZHU), Fen Lyu(AQNU), Weiyang Wang(UCAS), Heng Xu(NAOC), Yuanpei Yang(YNU), Wenfei Yu(SHAO), Chunfeng Zhang(NAOC) and FAST FRB Key Science Project
on 8 Feb 2024; 03:07 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Pei Wang (wangpei@nao.cas.cn)

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Following the detection of FRB 20240114A by CHIME/FRB (ATel#16420), we conducted a series of targeted observations on January 28, January 29, February 1, and February 4, 2024, using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Each session lasted 30 minutes, with the central beam of FAST's 19-beam L-band Array pointed to RA (J2000) 21h27m39.888s, +04d21m0.36s (ATel#16420), and the data stream was recorded with a sampling time of 49.152 microsecond for 4096 frequency channels.

Here we report 38 bursts of FRB 20240114A detected during the observation series, implying an average burst rate of ~20/h, above the 0.015 Jy ms fluence threshold of FAST (Li et al., 2021). The brightest burst was observed at the topocentric burst arrival time of UTC 2024-01-29 05:13:01. Averaging over the entire FAST observing band of 1.0-1.5 GHz, we observed the brightest burst at a preliminary fluence of 156.8±1.9 mJy ms with an effective pulse width of 1.27 ms. The best Dispersion measure (DM) and rotation measure (RM) values of the brightest burst were consistent with previous observational results (ATel#16420, ATel#16430, ATel#16432). We detected a ~ 96% degree of linear polarization and a ~ 25% degree of circular polarization in the burst.

Except for a few bright events, the flux densities of the most bursts we detected were in the range of 10-30 mJy. We note that these bursts were primarily observed in the frequency range of 1.0-1.2 GHz, exhibiting band-limited emission (< 100 MHz) feature distinct from that reported from Parkes (ATel#16430).

Given the low fluence and low frequency of the bursts from the FAST observations, we call for more follow-up monitoring efforts at a lower frequency band (≤ 1 GHz) to obtain a more comprehensive spectrum. We also encourage radio interferometric observations to localize FRB 20240114A further.

Shin, K., et al. 2024, The Astronomer's Telegram, 16420, 1
Uttarkar, P. A., Kumar, P., Lower, M. E., et al. 2024, The Astronomer's Telegram, 16430, 1
Ould-Boukattine, O. S., Hessels, J. W.T.,Kirsten, F., et al. 2024, The Astronomer's Telegram, 16432, 1
Li, D.; Wang, P.; Zhu, W.~W. et al., 2021, Nature, 598, 267.