{
  "circularId": 36167,
  "subject": "GRB 240418A: NOT optical upper limits",
  "body": "D. B. Malesani (DAWN/NBI and Radboud Univ.) and A. C. Casasbuenas (Univ. La Laguna and NOT) report on behalf of a larger collaboration.\n\nWe have observed the field of GRB 240418A (Siegel et al., GCN 36162) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations were carried out under poor sky transparency, and consisted of images in the SDSS r and z bands (mean epochs 3.19 and 3.37 hr after trigger, respectively).\n\nWithin or close to the localization error circle of the X-ray afterglow (Evans et al., GCN 36166), we detect no object in either filter, down to limiting AB magnitudes r > 22, z > 20.4, calibrated against nearby stars from the Pan-STARRS catalog.",
  "eventId": "GRB 240418A",
  "createdOn": 1713487840973,
  "bibcode": "2024GCN.36167....1M",
  "submitter": "Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl>",
  "submittedHow": "web"
}