GCN Circular 38320
Subject
GRB 241026A: radio detection with the VLA
Event
Date
2024-11-26T12:03:32Z (a year 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 23:07:34 UT on 2024 Oct 30 (T_mid = 4.05 days post-burst)
the Karl G. Jansky VLA observed the field of GRB 241026A
(Fermi GBM team, GCN 37894; Melandri et al., GCN 37896;
Li et al., GCN 37909; SVOM team, GCN 37921; Zhang et al.,
GCN 37924; Pal et al., GCN 37929) in three bands,
with central frequencies of 6, 10 and 15 GHz.
The standard 3C286 was used as bandpass and flux density
calibrator, while J1927+6117 was used as phase calibrator.
From a preliminary analysis, an unresolved radio source
is clearly detected at a position (J2000):
RA: 19:33:36.063 +- 0.001
Dec: +57:59:09.06 +- 0.01
consistent with the optical (Moskvitin et al., GCN 37899;
Watson et al., GCN 37900; Zheng et al., GCN 37903;
Shrestha et al., GCN 37913; Mohan et al., GCN 37918;
Moskvitin et al., GCN 37922; Wang et al., GCN 37928;
Moskvitin et al., GCN 37953; Rossi et al., GCN 37969;
Moskvitin et al., GCN 38028) and X-ray (Osborne et al.,
GCN 37904) position of the transient.
The preliminary analysis yields the following results:
================================================================
T_mid Freq Peak r.m.s. Beam PA
[days] [GHz] [uJy/b] [uJy/b] [arcsec^2] [deg]
================================================================
4.05 6 67 7 0.33x0.27 12
4.05 10 196 7 0.20x0.17 -0.7
4.05 15 330 7 0.14x0.12 24
================================================================
No source is detected with a >3sigma confidence at the
aforementioned position in previous radio surveys (NVSS,
VLASS), all of which have r.m.s. noise levels above
100 uJy/b.
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.