S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti
(INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),
N. Omodei (Stanford Univ.)
At 23:33:30 UT on 2023 August 23 (T_mid = 5.02 days post-burst) the
Karl G. Jansky VLA observed the field of GRB 230818A (Fermi GBM
team, GCN 34478; Tohuvavohu et al., GCN 34479) at a central
frequency of 6 and 10 GHz.
The standard J1331+3030 was used as bandpass and flux density
calibrator, while J1912+3740 was used as phase calibrator.
From a preliminary analysis, we do not detect the radio counterpart
of GRB 230818A. The r.m.s. noise level of the images is
11 uJy/beam and 13 uJy/beam at 6 and 10 GHz, respectively.
The synthesized beams are 0.44 x 0.89 arcsec (PA: 81 deg) at 6 GHz
and 0.28 x 0.24 arcsec (PA: -70 deg) at 10 GHz.
We would like to thank the staff of the VLA for approving, executing,
and processing the observations.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
These observations were carried out as part of project SF161095,
approved in the framework of the Fermi - NRAO joint program agreement.