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GCN Circular 39919

Subject

GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate

Date

2025-03-29T09:37:08Z (2 days ago)

Edited On

2025-03-31T02:03:51Z (19 hours ago)

From

Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo@ucd.ie>

Edited By

Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl>

Via

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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, 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, in particular Vincent Megevand and Rob van Holstein.