VLA search for persistent and bursting emission from SGR 1935+2154

ATel #13690; Vikram Ravi (Caltech), Gregg Hallinan (Caltech), Casey J Law (Caltech) on behalf of the realfast and STARE2 collaborations
on 30 Apr 2020; 00:47 UT
Credential Certification: Vikram Ravi (v.vikram.ravi@gmail.com)

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We report on publicly available Karl. G. Jansky VLA observations of SGR 1935+2154 obtained on 2020 Apr 29 17:40 UTC. SGR 1935+2154 is a currently active magnetar (GCNs 27657, 27659) that has emitted several bright high-energy flares since 2020 Apr 27. A millisecond-timescale radio burst with properties analogous to extragalactic fast radio bursts likely originating from this object has also been detected on 2020 Apr 28 (ATels 13681, 13684). The radio burst was coincident in time with a short hard X-ray flare (ATels 13685, 13686, 13687, 13688). Wideband data were obtained at center frequencies of 6 GHz (C-band) and 22 GHz (K-band) with the VLA in its C configuration. The image rms noise levels at the position of SGR 1935+2154 were 15 uJy and 18 uJy in the C- and K-band observations respectively. No persistent radio source was detected at the position of SGR 1935+2154, with preliminary 3sigma upper limits of 45 uJy and 54 uJy in the C and K bands respectively. The realfast commensal fast transient search system ran a full FRB search (DM = 0 - 3000, time widths 20 - 160 ms) on the VLA C band data with a sampling time of 20 ms. No detections were found stronger than 7.5 sigma, corresponding to an 8 sigma fluence limit of 0.2 Jy ms. We thank the staff of the VLA for rapidly scheduling and carrying out these observations for the benefit of the community. Further radio monitoring is encouraged.

Radio images of the field of SGR 1935+2154.