A bright burst detected at 2 GHz from the repeating FRB 20201124A

ATel #15285; Kazuhiro Takefuji, Yasuhiro Murata (JAXA), Sota Ikebe, Toshio Terasawa, Sujin Eie (Univ. of Tokyo), Syunsaku Suzuki, Mareki Honma, Takuya Akahori, Tomoaki Oyama (National Astronomical Observatory of Japan), Shintaro Yoshiura (National Astronomical Observatory of Japan; Univ. of Melbourne), Yoshinori Yonekura (Ibaraki Univ.), Kotaro Niinuma (Yamaguchi Univ.), Shota Kisaka (Hiroshima Univ.), and Teruaki Enoto (RIKEN)
on 18 Mar 2022; 05:57 UT
Credential Certification: Teruaki Enoto (teruaki.enoto@gmail.com)

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The repeating fast radio burst (FRB), FRB 20201124A, at an estimated redshift of z = 0.098 +/- 0.002 (ATels #14515; #14516), was previously active (ATels #14497; #14502; #14508) in March-April 2021, and started a possible new active phase in September 2021 (ATel #14933).

Following the recent reports of these FRB activities on January 23, 24, 26, and February 1, 2022 (ATels #15190; #15192; #15197), we made an observing session for this FRB with the 64-m radio dish of Usuda Deep Space Center (UDSC)/JAXA for 8 hours on February 18, 2022, 07:11:00-15:14:00 UT, at a central frequency of 2258 MHz with a total bandwidth of 128 MHz for a right-handed polarization mode. We detected a bright burst (peak S/N~349 for 1 ms integration) at an arrival time of 59628.598310779 MJD (14:21:34.05133 UT). The best-estimate of dispersion measure was 411.54 pc/cc (+/- 0.50 pc/cc). We noticed a digitization artifact (Jenet and Anderson, 1998) on the dedispersed waveshape, and derived the fluence lower limit at 199 Jy ms with +/-11 % uncertainty. (We calibrated the system sensitivity by observing 3C147 before and after the FRB observation.) No other bursts above S/N=10 (corresponding to a peak flux density of 3.2 Jy) were detected during this observing session. We have been still building a data analysis pipeline for FRBs, and it took a month from the observation to this report. Correction for the digitization artifact will be performed in our future analysis.

The frequency of the detection, 2.2-2.3 GHz, is the highest end of the multi-wavelength coverage of this repeating FRB reported so far. The fluence > 199 Jy ms is comparable to the brightest events detected from this FRB source at 1.3 GHz (e.g., 334 Jy ms reported in ATel #14556; and >771 Jy ms in ATel #15192). It is also comparable to the high-end fluence (100-400 Jy ms) of giant radio pulses from the Crab pulsar observed at 2.2-2.3 GHz with the same radio dish for a total of 42 hours (Enoto et al., 2021).

Jenet, F. A., and Anderson, S. B., 1998, Pub. Astron. Soc. Pacific, 110, 1467-1478 Enoto, T., et al. 2021, Science, 372, 187-190, Supplementary Material, Figure S8 and Table S5.

Waterfall plot of the detected burst