GCN Circular 40970
Subject
EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
Event
Date
2025-07-05T10:56:20Z (20 hours ago)
From
Roberto Ricci at INAF-IRA <ricci@ira.inaf.it>
Via
Web form
Yu-Han Yang, Niccolo Passaleva, Rosa L. Becerra, Roberto Ricci, Eleonora Troja (U. Rome) report on behalf of the ERC BHianca team:
We observed the field of GRB 250704B/EP250704a (Wang et al. GCN 40940; Li et al. GCN 40491) with the HAWKI imager on the ESO VLT UT4 (Yepun) camera. Our observations were carried out approximately at T_0+20 hr in the filters J and Ks.
At the position of the optical afterglow (Schneider et al. GCN 40942; Malesani et al. 40945), the NIR counterpart is clearly detected in all filters at a preliminary magnitude of J~19.5 AB,
calibrated to nearby stars from 2MASS catalog (Skrutskie et al. 2006) and not corrected by the Galactic extinction.
This result is consistent with the relatively flat light curve inferred from other observations (Perez-Garcia et al., GCN 40957; Gillanders et al., GCN 40958; Xin et al., GCN 40960;
Mohan et al., GCN 40962).
We thank the staff at the VLT, especially Thomas Szeifert, for the rapid execution of these observations.