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GCN Circular 33309

Subject
GRB 230205A: 6 GHz VLA observations
Date
2023-02-09T22:07:28Z (a year ago)
From
Genevieve Schroeder at Northwestern University <genevieveschroeder2023@u.northwestern.edu>
G. Schroeder, J. C. Rastinejad, W. Fong, C. D. Kilpatrick, A. E. Nugent
(Northwestern), E. Berger (Harvard), T. Laskar (Utah) report:

"We observed the position of the possibly short GRB 230205A (Ambrosi et al,
GCN 33271; Sakamoto et al., GCN 33280) with the Karl G. Jansky Very Large
Array (VLA) under program 23A-296 (PI: Schroeder) beginning on 2023
February 8.25 UT (2.81 days post-burst) at a mean frequency of 6 GHz.


We detect a radio source with a flux of ~40 microJy at the position:


RA(J2000) = 13:28:16.838

Dec(J2000) = +46:43:32.87


with an uncertainty of ~0.5" in each coordinate. This position is on the
outskirts of the XRT position (Goad et al. GCN 33275), on the NW edge. The
radio source position is consistent with the position of the optical source
reported by Urata et al. GCN 33307, although with a slight offset of
~0.85". If we assume this optical source is the host galaxy of GRB 230205A
and the radio source is afterglow, we find a probability of chance
coincidence of Pcc ~ 0.003 (Bloom et al. 2002). Alternatively, the detected
radio emission could originate from the host. In contrast, the radio source
is offset by ~3.6" from the center of the cataloged optical source (SDSS
J132816.81+464329.8) mentioned by Tomasella et al. GCN 33302. If we instead
assume that SDSS J132816.81+464329.8 is the host galaxy of GRB 230205A, we
find Pcc ~ 0.02.


Further observations are planned to determine the variability of the radio
source. We thank the VLA staff for quickly approving and executing these
observations."
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