GCN Circular 41872
Subject
GRB 250917B: VLT/HAWK-I near-infrared observations
Event
Date
2025-09-18T20:03:34Z (3 days ago)
From
muskan.yadav@students.uniroma2.eu
Via
Web form
Muskan Yadav (U. Rome), Rosa L. Becerra (U. Rome) and Eleonora Troja (U. Rome) report on behalf of the ERC BHianca team:
We observed the field of GRB 250917B (Fermi GBM Team et al., GCN 41846; Caputo et al., GCN 41848) with the HAWKI imager on the ESO VLT UT4 (Yepun). Observations started on 2025-09-17 at 23:52:22 UT, approximately 0.7 days after the trigger, and were carried out in the Ks filter at an average seeing of 0.6".
Image subtraction against 2MASS Catalogue (Skrutskie et al. 2006) shows no new uncataloged source down to K~18.5 AB. Several fainter objects are visible within the BAT refined position (Parsotan et al., GCN 41868), however additional observations are required to assess their variability.
At the position of the Source 1 reported by Kennea et al. GCN 41851, our observation is dominated by the close bright star TYC 1059-317-1.
We thank the staff at the VLT, for the rapid execution of these observations.