{
  "bibcode": "2021GCN.30097....1W",
  "body": "Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Simone Dichiara\n(GSFC/UMD), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Oc��lotl Lopez\n(UNAM), Diego Gonzalez (UNAM), Margarita Pereyra (UNAM), Srihari Ravi (ASU), and\nEleonora Troja (GSFC/UMD) report:\n\nWe observed the field of the MAXI/GSC GRB 210528B (Sugawara et al., GCN Circ.,\n30094) with the DDOTI wide-field imager at the Observatorio Astron��mico Nacional\non Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) from 2021-05-29 04:07\nto 06:53 UTC (from 5.3 to 8.0 hours after the trigger).\n\nWe observed a region covering aproximately 7 degrees in RA and 10 degrees in\ndeclination (1 instrumental field or about 70 square degrees) including the\nentire MAXI/GSC uncertainty region centered on 15:58:09 +05:58:58 J2000\n(Sugawara et al., GCN Circ., 30094). We obtained 7860 seconds of exposure in the\nw filter. We obtained AB photometry by calibration against the APASS catalog.\n\nWithin the uncertainty region, we detect no likely candidate for the afterglow\nto our 5-sigma upper limits of w = 21.8.\n\nWe thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir.",
  "circularId": 30097,
  "createdOn": 1622298758000,
  "email": "alan@astro.unam.mx",
  "subject": "GRB 210528B: DDOTI Upper Limits on the Afterglow",
  "submitter": "Alan M Watson at UNAM  <alan@astro.unam.mx>",
  "eventId": "GRB 210528B"
}