GCN Circular 38966
Subject
GRB 241217A / EP241217B: radio detection with the VLA
Event
Date
2025-01-17T09:29:05Z (10 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 07:53:14 UT on 2024 Dec 22 (T_mid = 4.65 days post-burst)
the Karl G. Jansky VLA observed the field of GRB 241217A /
EP241217B (Brunet et al., GCN 38594; Williams et al., GCN 38599;
Zhou et al., GCN 38606; Ravasio et al., GCN 38625) in three bands,
with central frequencies of 6, 10 and 15 GHz.
The standard 3C147 was used as bandpass and flux density
calibrator, while J0530-2503 was used as phase calibrator.
From a preliminary analysis, an unresolved radio source
is tentatively detected at a position (J2000):
RA: 05:36:36.321 +- 0.003
Dec: -25:17:49.39 +- 0.04
consistent with the X-ray (Williams et al., GCN 38599), optical
(Qiu et al., GCN 38600; Freeburn et al., GCN 38642), and radio
(An et al., GCN 38750) 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]
================================================================
4.65 6 32 7 0.77x0.28 26
4.65 10 36 8 0.51x0.18 32
4.65 15 38 7 0.30x0.11 24
================================================================
No source is detected with a >3sigma confidence at the
aforementioned position in previous radio surveys (NVSS,
VLASS, RACS), 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.