GCN Circular 34118
Subject
GRB230628E: VLT optical identification of afterglow candidate
Date
2023-06-29T07:14:44Z (a year ago)
From
J. T. Palmerio at Observatoire de Paris - GEPI <jesse.palmerio@obspm.fr>
D. B. Malesani (Radboud Univ. and DAWN/NBI) and J. Palmerio (GEPI / Paris Obs.) report on behalf of the STARGATE collaboration:
We observed the field of GRB 230628E (Salvaggio et al., GCN 34110) with the ESO VLT UT3 (Melipal) equipped with the X-shooter acquisition camera.
In a single 30 s exposure acquired in the r band, with mid time June 29.0252 UT (2.17 hr after the GRB), we see a new object, very close to the Swift/XRT position, which is not visible in the Pan-STARRS images of this field. Its coordinates (J2000, calibrated against the Gaia catalog, 0.5" error) are:
RA = 11:27:23.60
Dec = -11:27:49.21
Preliminary photometry (against the Pan-STARRS catalog) yields a magnitude r = 21.2
We consider this object a strong candidate as the afterglow of GRB 230628E, due to its consistency with the X-ray position and lack of detection in the Pan-STARRS archival images.
Further observations are in progress. We acknowledge expert support from the observing staff in Paranal, in particular Eleonora Sani (to whom we wish a happy birthday), Thomas Romain (on his last observing night in Paranal), Ditte Slumstrup (who actually discovered the afterglow), and Thomas Rivinius.