{
  "subject": "GRB 261108A: FRAM-Auger optical limits",
  "eventId": "GRB 261108A",
  "circularId": 46189,
  "submittedHow": "email",
  "submitter": "Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>",
  "createdOn": 1794106023728,
  "body": "Martin Jelinek, Jan Strobl and Filip Novotny\n(ASU CAS Ondrejov, CZ),\n\nMartin Masek, Sergey Karpov, Petr Janecek, Jakub Jurysek,\nJan Ebr, Ronan Cunniffe, Petr Travnicek and Michael Prouza\n(Institute of Physics, Prague, CZ)\n\nreport:\n\nThe 30cm robotic telescope FRAM-Auger at the Pierre Auger\nObservatory (Cerro Los Leones, Malargue, Argentina) reacted\nrobotically to the SVOM/ECLAIRs alert of GRB 261108A (SVOM\nGRB 261108.05, cf. Lipunov et al., GCN 46188; Fermi GBM also\ntriggered at the same time, trigger 815793204), obtaining a\nseries of 32 R-band images of 60 s each, starting at\n01:29:44 UT, i.e. ~16 min after the trigger and ~2 min after\nthe alert was received, and continuing until ~55 min after\nthe trigger. The field was at an elevation of ~60 deg.\n\nWe do not detect any new source within the ECLAIRs error\ncircle, neither in single images nor in the combined frames,\nwhen comparing to the catalogue. Neither does a subtraction\nof the coadd of the second half of the series from the coadd\nof the first half reveal any variable source. We obtain the\nfollowing limits:\n\nT-T0[mid]  Images  Limit (Vega)\n~16 min    1       R_C > 17.0\n~26 min    16      R_C > 18.7\n~45 min    16      R_C > 18.7\n\nSingle images reach R_C ~ 17.0 throughout the series. The\nphotometry is calibrated against the Atlas-REFCAT2 catalogue\n(Tonry et al. 2018, ApJ, 867, 105) and is not corrected for\nGalactic extinction.\n"
}