{
  "bibcode": "2021GCN.30698....1L",
  "body": "Oc��lotl Lopez (UNAM),  Margarita Pereyra (UNAM), Alan M. Watson (UNAM), Nat\nButler (ASU), Rosa L. Becerra (UNAM), Simone Dichiara (GSFC/UMD), Alexander\nKutyrev (GSFC/UMD), William H. Lee (UNAM), Diego Gonzalez (UNAM), Srihari\nRavi (ASU), and\nEleonora Troja (GSFC/UMD) report:\n\nWe observed the field of the Fermi - GBM event GRB 210822B (Fermi\nCollaboration, GCN Circ. 30683) with the DDOTI wide-field imager at the\nObservatorio Astron��mico Nacional on Sierra San Pedro Martir (\nhttp://ddoti.astroscu.unam.mx) from 2021-08-23 05:28:21 to 06:11:11 UTC\n(12.85to 13.73 hours after the trigger).\n\nWe observed a region of 20.4 degrees in RA by 20.4 degrees in declination,\nwith a 3 x 2 grid, centered on the Fermi GBM Final Position RA:  238.17,\nDEC: +18.02 (J2000 degrees). This region contains 6 instrumental fields or\nabout 400 square degrees. We obtained 7.77 minutes of exposure per\ninstrumental field in the w filter. We obtained AB photometry by\ncalibration against the APASS catalog.\n\n\nComparing to the Pan-STARRS DR1 catalog, we detect no uncatalogued point\nsources to a 10-sigma limiting magnitude of w = 18.07 - 18.65\n\nWe thank the staff of the Observatorio Astron��mico Nacional in San Pedro\nMartir.",
  "circularId": 30698,
  "createdOn": 1629754759000,
  "email": "koclopez@astro.unam.mx",
  "subject": "GRB 210822B: DDOTI Upper Limits on the Afterglow",
  "submitter": "Kin O. C. L. Mendoza at Instituto de Astronoma, UNAM  <koclopez@astro.unam.mx>",
  "eventId": "GRB 210822B"
}