GCN Circular 43952
Subject
GRB 260208A: radio detection with the VLA
Event
Date
2026-03-10T09:40:09Z (a day 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),
L. Nava (INAF-OAB)
At 05:24:16 UT on 2026 February 10 (T_mid = 2.04 days
post-burst) the Karl G. Jansky VLA observed the field of
GRB 260208A (Fermi GBM team, GCN 43635, 43673; Fermi-LAT
team, GCN 43645; GECAM team, GCN 43658; Waratkar et al.,
GCN 43674; Cheung et al., GCN 43675; Kirschner et al.,
GCN 43896) in three bands, with central frequencies of 6,
10 and 15 GHz.
The standard 3C286 was used as bandpass, flux density
and phase calibrator.
From a preliminary analysis, an unresolved radio source
is detected at a position (J2000):
RA: 13:38:55.595 +- 0.001
Dec: +33:48:06.12 +- 0.01
consistent with the X-ray (Swift-XRT team, GCN 43652) and
optical (Podesta et al., GCN 43640; GOTO collaboration,
GCN 43641; SVOM/VT team, GCN 43655; ZTF collaboration,
GCN 43657; Dimple et al., GCN 43661; Magnani et al.,
GCN 43664; Gupta et al., GCN 43665; Volnova et al., GCN
43666, 43770, 43771; Bochenek et al., GCN 43676;
Pérez-Fournon et al., GCN 43694; Swift/UVOT team, GCN
43702) 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]
================================================================
2.04 6 59 7 1.57x0.31 -60
2.04 10 90 8 1.27x0.18 -57
2.04 15 125 10 1.02x0.14 -55
================================================================
No source is detected with a >3sigma confidence level at the
aforementioned position in the VLASS. However, the r.m.s. noise
level of the survey at the GRB location is approximately 130 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 SF181027,
approved in the framework of the Fermi - NRAO joint program agreement.