{
  "bibcode": "2021GCN.29937....1H",
  "body": "K. E. Heintz (Univ. of Iceland and DAWN/NBI), D. A. Perley (LJMU), D. B. \nMalesani (DTU Space), and A. A. Djupvik (NOT) report on behalf of a \nlarger collaboration:\n\nWe observed the location of the optical and X-ray afterglow of GRB \n210504A (Beardmore et al., GCN 29929; Breeveld & Beardmore, GCN 29933) \nusing the Nordic Optical Telescope (NOT) equipped with the ALFOSC\ncamera.  We obtained 3x300 s frames in the Sloan r-band filter, followed \nby 5x200s frames in the z-band filter.  Observations were carried out on \n2021-05-04 UT between 23:10 and 23:35 (9.3 hours after the BAT trigger \ntime given by Lien et al. (GCN 29930).\n\nThe optical afterglow is detected in the combined images.  We report a \nrefined position (J2000) of:\n\nRA:   14:49:34.04\nDec: -30:32:02.6\n\nNo source is visible at this location in Pan-STARRS reference imaging.\n\nThe r-band magnitude of the afterglow at the time of the observation is \nmeasured to be 20.95 +/- 0.05.\n\n\n\n\n\n\n\n\n\nDisclaimerNone",
  "circularId": 29937,
  "createdOn": 1620173745000,
  "email": "d.a.perley@ljmu.ac.uk",
  "subject": "GRB 210504A: NOT optical afterglow detection",
  "submitter": "Daniel Perley at Liverpool JMU  <d.a.perley@ljmu.ac.uk>",
  "eventId": "GRB 210504A"
}