GCN Circular 37569
Subject
GRB 240910A: radio detection with the VLA
Date
2024-09-20T12:28:03Z (6 months ago)
From
Stefano Giarratana at INAF-OAB <s.giarratana@ira.inaf.it>
Via
email
S. Giarratana (INAF-OAB), M. Giroletti (INAF-IRA),
G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),
N. Omodei (Stanford Univ.), O. S. Salafia (INAF-OAB)
At 05:42:45 UT on 2024 Sept 13 (T_mid = 3.10 days post-burst)
the Karl G. Jansky VLA observed the field of GRB 240910A
(Fermi GBM team, GCN 37441, 37464; SVOM team, GCN37445, 37503)
at a central frequency of 6, 10 and 15 GHz.
The standard 3C48 was used as bandpass and flux density
calibrator, while J0125-0005 was used as phase calibrator.
From a preliminary analysis, an unresolved radio source
is clearly detected at a position:
RA: 01:36:23.458 +- 0.003
Dec: -00:12:17.42 +- 0.05
consistent with the optical (GOTO collaboration, GCN 37459;
Jiang et al., GCN 37460) and X-ray (D'Ai et al., GCN 37461)
transient.
The surface brightness peak is 137 uJy/beam, 114 uJy/b and
86 uJy/beam at 6, 10 and 15 GHz, respectively.
The r.m.s. noise level of the images is 7 uJy/beam at 6 GHz,
7 uJy/b at 10 GHz and 9 uJy/b at 15 GHz.
The synthesized beams are 1.36x1.01 arcsec (PA: -48deg)
at 6 GHz, 0.79x0.63 arcsec (PA: -50deg) at 10 GHz
and 0.61x0.43 arcsec (PA: -56deg) at 15 GHz.
While no source is detected with a 3sigma confidence at the
aforementioned position in previous radio surveys (FIRST, NVSS,
VLASS, RACS), their r.m.s. noise levels (1sigma) is above
100 uJy/b. Therefore, we cannot exclude the contribution from
the GRB host galaxy yet.
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
Universities, Inc.
These observations were carried out as part of project SF171028,
approved in the framework of the Fermi - NRAO joint program agreement.