TITLE: GCN CIRCULAR NUMBER: 39521 SUBJECT: GRB 250225B: VLT/Xshooter imaging DATE: 25/02/27 17:12:33 GMT FROM: Yu-Han Yang at University of Rome Tor Vergata yyang@roma2.infn.it
Yu-Han Yang (U Rome), Eleonora Troja (U Rome), and Rosa Becerra (U Rome) report on behalf of the ERC BHianca team: We observed the field of GRB 250225B (Williams et al., GCN 39473) with the Xshooter spectrograph on the ESO VLT UT3 (Melipal). Observations began at T+38.0 hours and, due to visibility constraints, only 2x600s spectra were acquired. Using the acquisition and guiding (A&G) camera, imaging in the I filter was carried out at an average airmass of about 2.1. No source is detected at the position of the optical and nIR candidate counterpart (Schneider et al. GCN 39494, Yang et al. GCN 39495) down to a 3-sigma limit I>22.4 AB mag calibrated using nearby stars in the Legacy Survey DR10 (Dey et al. 2019) catalogue. Compared to our previous measurement (Yang et al. GCN 39495), these observations provide tentative evidence for fading by ~0.3 mag. Further observations are planned. We thank the staff at the VLT, for the rapid execution of these observations.
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