GRB 221009A/Swift J1913.1+1946: eMERLIN observations

We observed the position of GRB 221009A (Swift J1913.1+1946; ATel #15650, ATel #15651) with the eMERLIN at 1.51GHz beginning at 17:55UT on 11th October for a total of 6 hours. OQ208 was used as the flux and bandpass calibrator while J1905+1943 was used as the complex gain calibrator. We detect an unresolved source at a position consistent with the one reported in ATel #15651 with a (preliminary) flux density of ~4mJy. We are in the process of obtaining further radio observations. We thank the e-MERLIN staff for the time allocation and their assistance with the observations.