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GCN Circular 34118

GRB230628E: VLT optical identification of afterglow candidate
2023-06-29T07:14:44Z (a year ago)
J. T. Palmerio at Observatoire de Paris - GEPI <>
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.
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