{
  "bibcode": "2023GCN.33243....1G",
  "body": "S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti \n(INAF-IRA), T. An (Shanghai A.O.), G. Anderson (Curtin University), P. \nAtri (ASTRON), J. S. Bright (University of Oxford), R. Fender \n(University of Oxford), G. Ghirlanda (INAF-OAB), J. K. Leung (University \nof Sydney, CSIRO), B. Marcote (JIV-ERIC), M. P��rez-Torres (IAA-CSIC), L. \nRhodes (University of Oxford), O. S. Salafia (INAF-OAB), J. Yang (OSO)\n\nOn UT 2022 November 18 and 21 (40 and 43 days post-burst) we observed \nthe radio counterpart of GRB 221009A (Dichiara et al, GCN 32632; Veres \net al., GCN 32636) with the European VLBI Network (EVN) at a central \nfrequency of 8.3 and 5 GHz, respectively.\n\n From a preliminary analysis, the source is clearly detected at both \nfrequencies with >30 sigma significance. The 8.3 GHz surface brightness \npeak is ~1.3 mJ/beam. The synthesized beam is 0.9 x 0.5 mas (PA = 7.7 \ndeg). The 5 GHz surface brightness peak is ~1.4 mJy/beam. The \nsynthesized beam is 1.7 x 0.9 mas (PA = 9.25 deg).\n\nThe source is found at a position within ~1 mas of the one previously \nreported by Atri et al., GCN 32907 with the VLBA at 15.2 GHz. The offset \nis most likely accounted for by systematics.\n\nAll the results presented here are preliminary. Further analysis is in \nprogress. We will report the final results in a forthcoming publication.\n\nWe would like to thank the directors and staff of all the EVN telescopes \nfor approving, executing, and processing these out-of-session ToO \nobservations.\n\nThe European VLBI Network is a joint facility of independent European, \nAfrican, Asian, and North American radio astronomy institutes. \nScientific results from data presented in this publication are derived \nfrom the following EVN project code: RG013.",
  "circularId": 33243,
  "createdOn": 1675248085000,
  "email": "s.giarratana@ira.inaf.it",
  "subject": "GRB 221009A: radio afterglow detection with the EVN",
  "submitter": "Stefano Giarratana at University of Bologna  <s.giarratana@ira.inaf.it>",
  "eventId": "GRB 221009A"
}