Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 30078

Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
2021-05-25T16:25:45Z (3 years ago)
Emma Margarita Pereyra Talamantes at IA-UNAM Ensenada <>
Margarita Pereyra (UNAM), Nat Butler (ASU), Alan M. Watson (UNAM), Eleonora
Troja (GSFC/UMD),  Simone Dichiara (GSFC/UMD), Rosa L. Becerra (UNAM),
William H. Lee (UNAM), Oc��lotl L��pez,  Diego Gonzalez (UNAM), Alexander
Kutyrev (GSFC/UMD), and Srihari Ravi (ASU), report:

We observed the field of the likely long Fermi GRB 210524B  (trigger
643548039, GCN #30074, Fermi GBM Team) with the DDOTI/OAN wide-field imager
at the Observatorio Astron��mico Nacional on Sierra San Pedro M��rtir ( on 2021-05-25 from 03:32:24 to 04:48:24 UTC
(16.19 to 17.46 hours  after the event).

We observed a region of 20.4 degrees in RA by 20.4 degrees in declination,
with a 3 x 2 grid, centered on the Fermi GBM Final Position RA: 148.460
DEC: 7.79 (J2000 degrees). This region contains 6 instrumental fields or
about 400 square degrees. We obtained 600 to 720 seconds of exposure per
instrumental field in the w filter. We obtained AB photometry by
calibration against the APASS catalog.

We detect no likely candidate for the afterglow to our 10-sigma upper
limits of w = 18.52 - 18.84 (inter-quartile).

We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
Looking for U.S. government information and services? Visit