TITLE:   GCN CIRCULAR
NUMBER:  46191
SUBJECT: EP261105a: VLT/HAWK-I nIR detection
DATE:    26/11/08 06:57:43 GMT
FROM:    Hira Waseem at Università degli Studi di Roma "La Sapienza" <hirawaseem633@gmail.com>

H. Waseem, M. El Kabir, M. Yadav, R. Ricci  and E. Troja (U Rome) report on behalf of the ERC BHianca team:

We observed the field of EP261105a (Guo et al., GCN 46155; Guo et al., GCN 46168) with HAWK-I on the ESO Very Large Telescope (VLT). Observations started on 2026-11-07 at 08:12 UT, about 46 hours after the trigger, and were performed using the J and Ks filters at an airmass of ~1.2 and an average seeing of ~0.5 arcsec. 

Photometric calibration was performed using nearby stars from the 2MASS catalogue. Magnitudes are reported in the AB system and are not corrected for Galactic extinction. At the position of the optical counterpart (Ma et al., GCN 46160; Waseem et al., GCN 46170), we detect the source at a preliminary magnitude of J~24 AB. 

If associated with the nearby galaxy at z_phot~0.055, the observed magnitudes would be much fainter than AT2017gfo at a similar epoch. Our observations continue to be consistent with a fading non-thermal afterglow, and the presence of an underlying galaxy cannot be yet constrained. 

We thank the staff at the VLT for the rapid execution of these observations.