{
  "subject": "GRB 241105A: VLT/FORS2 optical afterglow rapid fading",
  "eventId": "GRB 241105A",
  "submittedHow": "web",
  "bibcode": "2024GCN.38111....1D",
  "createdOn": 1730991577489,
  "circularId": 38111,
  "submitter": "Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra@roma2.infn.it>",
  "format": "text/plain",
  "body": "Simone Dichiara (PSU), Eleonora Troja (U Rome), Rosa L. Becerra (U Rome), Yu-Han Yang (U Rome)  report:\n\nWe 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\"). \n\nWe detect the optical counterpart (Julakanti et al., GCN 38088) at a preliminary magnitude \nR ~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. \n\nFurther observations are planned. \n\nWe thank the staff at the VLT, especially Maria Jose Rain, for the rapid execution of these observations."
}