TITLE:   GCN CIRCULAR
NUMBER:  29028
SUBJECT: GRB 201015A: 5-GHz radio afterglow detection with the EVN
DATE:    20/12/11 17:07:03 GMT
FROM:    Benito Marcote at JIVE  <marcote@jive.eu>

B. Marcote (JIVE), M. Ribó (Univ. of Barcelona), J. M. Paredes (Univ. of Barcelona), M. Giroletti (INAF/IRA), S. Giarratana (Univ. of Bologna, INAF/IRA), G. Ghirlanda (INAF/OABrera)

We observed the radio counterpart of GRB 201015A (D'Elia et al., GCN 28632) with the European VLBI Network (EVN) on 9 November 2020 and 1 December 2020 at a central frequency of 5.0 GHz.

Preliminary analysis reports the detection of a compact radio source at a >8-sigma confidence level in both epochs at a consistent position of:

RA (J2000) = 23h37m16.4223s
Dec (J2000) = +53d24'56.439"

With an uncertainty of ~1 mas on each coordinate. The synthesized beams are 1.1 x 2.1 mas (PA = 7.1 deg) and 3.1 x 3.6 mas (PA = -29 deg) for the first and second epoch, respectively. We note that this position is consistent with the one previously reported by the VLA (Fong et al. GCN 28688) and eMERLIN (Giarratana et al. GCN 28939).

Further analysis is in progress.



We thank the directors and staff of all the EVN telescopes for making this target of opportunity observation possible.
The European VLBI Network is a joint facility of independent European, African, Asian, and North American radio astronomy institutes. Scientific results from data presented in this publication are derived from the following EVN project code: RM016. e-VLBI research infrastructure in Europe is supported by the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement number RI-261525 NEXPReS. e-MERLIN is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC.