{
  "eventId": "GRB 250103B",
  "subject": "GRB 250103B: LCOGT Optical Upper Limit",
  "createdOn": 1735933492919,
  "submitter": "Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>",
  "bibcode": "2025GCN.38805....1S",
  "circularId": 38805,
  "submittedHow": "email",
  "body": "R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:\n\nWe observed the Swift GRB 250103B field (Eyles-Ferris et al., GCN 38796)  with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on January 3, from 18:51 to 19:23 UT (corresponding to 4.12 to 4.65 hours after the GRB trigger time) with the Bessel I and R filters.\n\nWe performed a series of 3x300s exposures in I-band and R-band.  We do not detect a source within the  XRT error region in either band.\n\nThe following 5-sigma upper limits are calculated using the USNO-B1.0 catalog as reference:\n\nR > 23.0\nI > 22.1\n\nThese magnitudes are not corrected for galactic extinction.\n"
}