TITLE: GCN CIRCULAR NUMBER: 38111 SUBJECT: GRB 241105A: VLT/FORS2 optical afterglow rapid fading DATE: 24/11/07 14:59:37 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma rosa.becerra@roma2.infn.it
Simone Dichiara (PSU), Eleonora Troja (U Rome), Rosa L. Becerra (U Rome), Yu-Han Yang (U Rome) report:
We observed the field of GRB 241105A (Fermi GBM team, GCN 38085; DeLaunay et al., GCN 38091; Konus-Wind team, GCN 38103) with the FORS2 imager on the ESO VLT UT1 (Antu). Observations began 1.5 days after the trigger and were carried out in the R and z filters through good seeing conditions (0.8").
We detect the optical counterpart (Julakanti et al., GCN 38088) at a preliminary magnitude R ~22.5 AB mag calibrated using nearby stars in the Legacy Survey DR10 (Dey et al. 2019). Compared with earlier optical detections (Julakanti et al., GCN 38088; SVOM/VT team, GCN 38099; Izzo et al. GCN 38097; Hu et al., GCN 38106), our observations show a rapid decline of the afterglow brightness, consistent with a power-law of slope ~-1.7.
Further observations are planned.
We thank the staff at the VLT, especially Maria Jose Rain, for the rapid execution of these observations.
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