TITLE: GCN CIRCULAR NUMBER: 39919 SUBJECT: GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate DATE: 25/03/29 09:37:08 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group antonio.martin-carrillo@ucd.ie
B. Schneider (LAM), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), G. Corcoran (UCD), report on behalf of the Stargate collaboration:
We observed the location of the SVOM/ECLAIRs GRB 250328A (Brunet et al., GCN 39910) using the ESO/VLT UT4 (Yepun) equipped with the HAWK-I camera. Observations started on March 29 at 07:13:31 UT (14.3 hr after the SVOM trigger). A series of 15 images of 60 s were obtained in the J-band.
Consistent with the location of the X-ray Swift/XRT [source #2](https://www.swift.ac.uk/SVOM/SVOM_FIELD00006/), we detect an object which is not visible in the Legacy Survey, at coordinates:
RA(J2000) = 14:23:50.41 = 215.9601 Dec(J2000) = +25:55:55.0 = +25.9319
We measure J = 21.9 +/- 0.1 (AB) calibrated against nearby stars in the 2MASS catalogue.
This object is a viable afterglow candidate for GRB 250328A, although we note that we lack deep enough reference imaging in the J band, and the X-ray light curve of XRT source #2 does not show obvious fading. Further observations are thus required to robustly confirm the nature of this NIR and X-ray source.
We acknowledge excellent support from the ESO observing staff in Paranal.
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