{
  "createdOn": 1759389901674,
  "circularId": 42050,
  "bibcode": "2025GCN.42050....1D",
  "body": "A. de Ugarte Postigo (LAM), D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), B. Schneider (LAM), B. P. Gompertz (Birmingham), A. Martin-Carrillo (UCD) and J. Maiz Apellaniz (IAA-CSIC) report:\n\nWe observed the field of GRB 251001B (Fermi GBM team, GCN 42038; Beardmore et al. GCN 42039) using the 2.5 m Nordic Optical Telescope (NOT) equipped with ALFOSC. Observations started on 2 October 2025 at 02:37:23 UT (12.33 hr after the trigger) and consisted of 3x300 s and 5x200 s in the SDSS r and z bands, respectively.\n\nThe combined images reveal the presence of the afterglow identified by Gompertz et al. (GCN 42040; An et al. GCN 42041; Strausbaugh & Cucchiara GCN 42043; O'Neill et al. GCN 42046) at a magnitude of r = 21.54 +/- 0.06 (AB) calibrated against field stars of the Pan-STARRS catalogue and not corrected by Galactic extinction.",
  "subject": "GRB 251001B: NOT optical observations",
  "submittedHow": "email",
  "submitter": "Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo@gmail.com>",
  "eventId": "GRB 251001B"
}