High Frequency Radio Observations of FRB 20201124A at 2.26 GHz using the Deep Space Network

ATel #14519; Aaron B. Pearlman (Caltech, McGill University, McGill Space Institute), Walid A. Majid (JPL, Caltech), Thomas A. Prince (Caltech, JPL), Karishma Bansal (JPL), Charles J. Naudet (JPL), Jonathon Kocz (UC Berkeley)
on 7 Apr 2021; 05:21 UT
Credential Certification: Aaron B. Pearlman (aaron.b.pearlman@caltech.edu)

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FRB 20201124A is a repeating fast radio burst (FRB) source that was discovered using the CHIME/FRB radio telescope (ATel #14497). Over the past few weeks, multiple radio bursts have been detected from FRB 20201124A by several instruments, including the CHIME/FRB (ATel #14497), ASKAP (ATel #14502; ATel #14508), and FAST (ATel #14518) radio telescopes. These observations suggest that FRB 20201124A has entered into a highly active state and is capable of producing emission over a wide range of radio frequencies.

We report the results of a radio observation of FRB 20201124A using the Deep Space Network (DSN) 34 m diameter radio telescope (DSS-13) in Goldstone, California. We carried out a continuous radio observation on 31 March 2021 (MJD 59304), starting at 21:18:46 (UTC), using the S-band receiver (center frequency: 2.26 GHz) outfitted on DSS-13. The total duration of the observation was 10680 s. Channelized power spectral density measurements were recorded in a digital polyphase filterbank across a total bandwidth of 110 MHz with a frequency and time resolution of 0.625 MHz and 102.4 us, respectively.

We dedispersed the S-band data with trial DMs between 300 and 500 pc cm^-3 and carried out a search for radio bursts using a Fourier domain matched filtering algorithm, where each dedispersed time-series was convolved with boxcar functions with logarithmically spaced widths between 102.4 us and 100 ms. Candidates with detection signal-to-noise ratios (S/N) above 7.0 were saved and visually inspected for verification. No radio bursts were detected during our observation above a S/N threshold of 7.0.

This observation was performed using the best-fit localization of FRB 20201124A reported by the CHIME/FRB collaboration in ATel #14497: RA (J2000) 05:08, DEC (J2000) +26:11. The angular offset between our pointing position and the best-fit position from the ASKAP localization of FRB 20210402A (ATel #14515) is 7.4 arcmin. However, we note that the beam size of DSS-13 is roughly 16.4 arcmin at 2.26 GHz, and this observation with DSS-13 would have also been sensitive to detecting radio bursts at S-band from the best-fit position of FRB 20210402A determined by ASKAP, if they had comparable fluences to the bursts reported in ATels #14502 and #14508.

We place a 7-sigma upper limit of 5.4 Jy ms on the fluence of radio bursts during this observation, assuming a burst width of 1 ms at 2.26 GHz. This upper limit corresponds to a fluence detection threshold at the best-fit position of FRB 20210402A (ATel #14515). We have applied a correction factor of 1.8 due to the angular offset of our pointing position, which was derived assuming a two-dimensional Gaussian beam model with a full width at half maximum (FWHM) of 16.4 arcmin.

We are grateful to the DSS-13 operators and the CHIME/FRB collaboration for their support of these observations.