TITLE: GCN CIRCULAR NUMBER: 44399 SUBJECT: GRB 250328A: VLT host galaxy discovery and redshift z = 1.250 DATE: 26/04/23 12:50:54 GMT FROM: Nusrin Habeeb at University of Leicester <nh312@leicester.ac.uk> A. Saccardi (CEA/Irfu), B. Schneider (LAM), S. D. Vergani (LUX-Paris Obs.), D. B. Malesani (DAWN/NBI and Radboud), N. Habeeb (U. Leicester), R. Brivio (INAF/OAB), G. Corcoran (UCD), J.-L. Atteia (IRAP), report on behalf of the Stargate collaboration: We observed the location of the optical/NIR counterpart (Schneider et al., GCN 39919, 39920; Li et. al, GCN 39923; Li et. al, GCN 39936; Kumar et. al, GCN 39946; Klingler et. al, GCN 39968; Pankov et al., GCN 40001) of the SVOM GRB 250328A (Brunet et al., GCN 39910), using the ESO VLT UT1 (Antu) equipped with the FORS2 imager. A 20 min exposure R-band observation was carried out at 04:05:01 UT on 2026 April 19 (386.46 days after the SVOM trigger). Consistent with the afterglow position, an object is clearly identified with a magnitude r = 24.51 +/- 0.09, calibrated against the Pan-STARRS catalog and not corrected for Galactic extinction. Its coordinates (J2000) are: RA = 14:23:50.45 Dec = +25:55:55.09 Given the spatial coincidence with the GRB afterglow (<0.5"), this is the likely host galaxy of GRB 250328A. Spectroscopic follow-up observations of this object were secured using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph, covering the wavelength range 3000-21000 AA. We obtained four spectra of 1200 s each starting at 03:28:04 on 2026 April 23, i.e. about 390.44 days after the SVOM trigger. Faint emission lines are detected in the visible and near-infrared arms, which we identify as the [O III] 4959,5007 doublet, H-beta, and the [O II] 3726,3729 doublet, all at a common redshift of z = 1.250. This is thus the redshift of the likely host galaxy of GRB 250328A. We acknowledge excellent support from the ESO staff in Paranal, in particular Boris Haeussler, Diego Parraguez, Felipe Gaete, Hannah Osborne, Luca Sbordone, Matias Jones, and Thomas Rivinius. View this GCN Circular online at https://gcn.nasa.gov/circulars/44399. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...