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GCN Circular 34552

Subject
GRB 230812B: radio detection with the VLA
Date
2023-08-25T18:17:37Z (8 months ago)
From
Stefano Giarratana at University of Bologna <s.giarratana@ira.inaf.it>
Via
email
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 01:52:24 UT on 2023 August 15 (T_mid = 2.3 days post-burst) the
Karl G. Jansky VLA observed the field of GRB 230812B (Fermi GBM
team, GCN 34386) at a central frequency of 6 and 10 GHz.

The standard J1331+3030 was used as bandpass and flux density
calibrator, while J1637+4717 was used as phase calibrator.

From a preliminary analysis, an unresolved radio source (Rhodes et al.,
GCN 34433; de Ugarte Postigo et al., GCN 34468) is clearly detected
at both frequencies at a position:

RA: 16:36:31.477 +- 0.001
Dec: +47:51:32.25 +- 0.02

The surface brightness peak is 230 uJy/beam and 196 uJy/beam at 6
and 10 GHz, respectively. The r.m.s. noise level of the images is
10 uJy/beam and 7 uJy/beam at 6 and 10 GHz, respectively.
The synthesized beams are 0.31 x 0.26 arcsec (PA: -45deg) at 6 GHz
and 0.20 x 0.16 arcsec (PA: -45deg) 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
Universities, Inc.

These observations were carried out as part of project SF161095,
approved in the framework of the Fermi - NRAO joint program agreement.

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