{
  "circularId": 39076,
  "submitter": "Christophe Adami at LAM <christophe.adami@lam.fr>",
  "bibcode": "2025GCN.39076....1A",
  "createdOn": 1738141735392,
  "submittedHow": "web",
  "eventId": "GRB 250128B",
  "format": "text/plain",
  "subject": "GRB 250128B: OHP/T193 optical upper limit",
  "body": "C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), S. Basa (LAM/OHP/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), A. Saccardi (CEA/Irfu), D. Turpin (CEA/Irfu), F. Schussler (CEA Paris-Saclay), M. Dennefeld (IAP), J. Palmerio (CEA/Irfu) report on behalf of a larger collaboration:\n\nWe observed the field of the GRB250128B (Fermi GBM team, GCN 39057; Evans et al., GCN 39058; Izzo et al., GCN 39059; Lipunow et al., GCN 39061; Ulaczyk et al., GCN 39062; Muers et al., GCN 39063; Osborne et al., GCN 39064; Lipunov et al., GCN 39067; Evans et al., GCN 39069) with the T193cm telescope at the Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained a total of 2490sec (1x30s + 1x300s + 3x720s) in the i-band using the red MISTRAL setting from 20250129_043822UT to 20250129_050703UT (mid-time ~12.5h after the trigger).\n\nIn the stacked image, we do not detect any new source at the XRT source position (Evans et al., GCN 39069) down to the following 3-sigma limit:\n\ni > 20.6\n\nThe photometric calibration was performed using nearby stars from the PanSTARRS catalog.\nWe acknowledge the excellent support from Observatoire de Haute-Provence, in particular Jean Balcaen, and the Sophie observer Alice Radcliffe"
}