TITLE:   GCN CIRCULAR
NUMBER:  34141
SUBJECT: GRB 230328B: LBT detection of the likely host galaxy
DATE:    23/07/04 14:14:34 GMT
FROM:    Andrea Rossi at INAF <andrea.rossi@inaf.it>

A. Rossi, E. Maiorano, and E. Palazzi (INAF-OAS) report on behalf of the CIBO collaboration:

We observed the field of the long GRB 230328B detected by Fermi-GBM  (Fermi GBM Team, GCN 33526; Dalessi et al., GCN 33531), Swift-BAT (Gropp et al., GCN 33527), AstroSat-CZTI (Waratkar et al., GCN 33532), GRBAlpha (Dafcikova et al., GCN 33543), and Konus-Wind (Svinkin et al., GCN 33544). We obtained 20 min of g'- and r'-band imaging with the LBC camera mounted on LBT (Mt Graham, AZ, USA) on 2023-06-23, ~3 months after the burst trigger. Observations were performed under mediocre weather conditions with a strong SW wind and thus an average seeing of ~2".

At the location of the optical afterglow (Pankov et al., GCN 33528; Belkin et al., GCN 33530; Lu et al., GCN 33534; Catapano et al., GCN 33535; Suresh et al., GCN 33536; Adami et al., GCN 33537; Gompertz et al., GCN 33538; Komesh et al., GCN 33539; Kumar et al., GCN 33547; Kugel et al., GCN 33550; Siegel et al., 33556; Pozanenko et al., GCN 33559), we detect a faint source which is likely the GRB host galaxy. We measure the following AB magnitudes:

g 24.2 +- 0.3
r 23.8 +- 0.2

calibrated against PanSTARRS field stars, and not corrected for the foreground Galactic extinction.

We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly D. Thompson, D. Gonzalez Huerta, F. Cusano and D. Paris, in obtaining these observations.