uGMRT localization of FRB20201124A

ATel #14538; Robert Wharton (MPIfR), Suryarao Bethapudi (MPIfR), Viswesh Marthi (NCRA), Robert Main (MPIfR), Dongzi Li (Caltech), Tasha Gautam (MPIfR), Hsiu-Hsien Lin (CITA), Laura Spitler (MPIfR), Ue-Li Pen (CITA)
on 9 Apr 2021; 16:22 UT
Credential Certification: Robert Wharton (wharton@mpifr-bonn.mpg.de)

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As reported in Atel #14529, we conducted observations towards the location of FRB20201124A with the upgraded Giant Metrewave Radio Telescope (uGMRT) at 550-750MHz and detected 35 bursts above a fluence of ~5 Jy ms in a 3 hr exposure. The brightest burst, detected at UTC 2021-04-05T14:39:57.856, has a fluence of 111+/- 6 Jy ms, more than twice as energetic as any other single burst. Using this burst, we have localized the FRB source to a position (epoch J2000) of (RA, Dec) = (05:08:03.459, +26:03:39.14). The 5 sigma statistical uncertainty of the position is 0.5 arcsec for RA and 0.25 arcsec for Dec. We do not include systematic effects here, but they should be less than 1 arcsec. This burst position is consistent with the VLA/realfast localization (ATel #14526) and the location of the persistent radio source (PRS) we reported (Atel #14529). However, it is offset by 2.8 arcsec from the ASKAP burst position (ATel #14515).

In addition to the brightest burst above, the other 34 detected bursts had fluences between 5-50 Jy ms, with an average of ~16 Jy ms. Averaging all of the bursts over the 3 hr exposure would result in a 50 uJy source. Thus we find it unlikely that the PRS is the average result of many bursts, unless there are thousands of undetected bursts below 5 Jy ms.

Below is a link to our 550-750 MHz images overplotted with the uGMRT localized FRB20201124A burst position with 5 sigma statistical uncertainty (magenta), PRS position with the 5 sigma statistical uncertainty (black), the ASKAP (green) and VLA/realfast (cyan) burst localizations, and the location of SDSS J050803.48+260338.0 (blue cross). The left panel shows the PRS integrated over a 40 minute scan, while the right panel shows the burst in a 3 second integration.

Persistent radio source and burst localization

The brightest burst, detected in a 3 sec image with a S/N of ~40, is shown here.

Burst image detection

The waterfall plots of the detected bursts can be found in the link below. Time samples and channel widths are 655.36 us, 781.25 kHz respectively, and bursts are de-dispersed to DM=411.0 pc/cc. Burst 14 was used for localization imaging.

Waterfall plots of the detected bursts