TITLE:   GCN CIRCULAR
NUMBER:  40134
SUBJECT: GRB 250314A: e-MERLIN observations
DATE:    25/04/10 20:17:58 GMT
FROM:    Aishwarya L Thakur at INAF-IAPS, Rome <aishth@outlook.com>

A.L. Thakur [1], G. Bruni [1], L. Piro [1] and G. Gianfagna [1] report:

We observed the z=7.3 GRB 250314A (SVOM GCN 39719, VLT/X-shooter GCN 39732, GTC/OSIRIS+ GCN 39743), with the e-MERLIN radio telescope under project RR19004 (PI: Thakur) at 5 GHz starting from Mar 31 (~17 days post-GRB) for three runs of ~12 hours each.

1331+3030 was used for flux scale calibration, and 1332-0509 for complex gain. The beam size was 122x34 milli-arcsec. Data were reduced with the e-MERLIN pipeline and imaged with CASA. The image RMS was 18 uJy/beam.

We do not find statistically significant emission at a level above 5-sigma at the position of the NOT counterpart (GCN 39727) or in the broader 2x2 arcsec field. We thus set a 5-sigma upper limit of 90 uJy at 5 GHz. 

Further e-MERLIN observations are planned.

We thank the e-MERLIN director for promptly approving these DDT observations and acknowledge Justin Bray's excellent support in scheduling and executing them. e-MERLIN is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC, part of UK Research and Innovation.
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[1] INAF-IAPS