GCN Circular 44730
Subject
EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
Event
Date
2026-05-29T02:09:56Z (18 hours ago)
From
Massine El Kabir <m.elkabir@campus.unimib.it>
Via
Web form
M. El Kabir, Y. Yang and E. Troja (U Rome) report on behalf of the ERC BHianca team:
We observed the field of EP260527a (Yang et al., GCN 44718), likely associated with the short GRB 260527A (Svinkin et al., GCN 44722, Yu et al., GCN 44724; Kawakubo et al., GCN 44726), with the FORS2 and HAWK-I on the ESO Very Large Telescope (VLT). Observations started about 41.4 hrs after the GRB trigger and were performed at an airmass of ~1.2 in excellent conditions. The field was imaged using the r, z, J and K filters.
Photometric calibration was performed using nearby stars from the Pan-STARRS and 2MASS catalogues. Magnitudes are reported in the AB system and are not corrected for Galactic extinction. At the position of the optical counterpart (Aguilar-Ruiz et al., GCN 44719; Li et al., GCN 44720; Busmann et al.44728; Corcoran et al. GCN 44729 ), we detect a source with the following preliminary magnitude:
z = 23.1 +/- 0.1
J = 23.0 +/- 0.1
Compared to earlier observations (Aguilar-Ruiz et al., GCN 44719), our measurements suggest a rapid fading of the afterglow, consistent with the observed X-ray behavior (Yang et al. GCN, 44725).
We thank the staff at the VLT for the rapid execution of these observations.