{
  "circularId": 40727,
  "submittedHow": "web",
  "body": "A. de Ugarte Postigo (LAM), A. Martin-Carrillo (UCD), G. Corcoran (UCD), D. B. Malesani (DAWN/NBI and Radboud), D. Xu (NAOC), L. Cotter (UCD), B. P. Gompertz (U. Birmingham), A. A. Djupvik (NOT), L. Fuglsang (NOT), report on behalf of a larger collaboration.\n\nWe observed the field of EP250612a / GRB 250612B detected by EP (Hua et al., GCN 40700) and Fermi (Fermi GBM team, GCN 40702), using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT). We obtained 12x100 s exposures in the SDSS r-band, starting at 23:19 UT on 2025-05-13 (1.952 days after the EP trigger).\n\nAt J2000 coordinates RA:15:18:36.667, DEC: -26:46:03.624 (error 0.5”), consistent with those by Li et al. (GCN 40716), the optical counterpart is detected in our stacked image with a preliminary magnitude:\n\nr = 23.59 +/- 0.22  (AB).\n\nThe photometric calibration was performed using nearby stars from the Pan-STARRS catalog and the magnitudes are not corrected for Galactic extinction.",
  "eventId": "EP250612a",
  "submitter": "Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo@ucd.ie>",
  "format": "text/plain",
  "bibcode": "2025GCN.40727....1D",
  "createdOn": 1749889774614,
  "subject": "EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate"
}