TITLE:   GCN CIRCULAR
NUMBER:  30104
SUBJECT: GRB 210529B: DDOTI Upper Limits on the Afterglow
DATE:    21/05/31 02:02:56 GMT
FROM:    Kin O. C. L. Mendoza at Instituto de Astronoma, UNAM  <koclopez@astro.unam.mx>

Océlotl Lopez (UNAM), Margarita Pereyra (UNAM), Rosa L. Becerra (UNAM), Nat
Butler (ASU), Alan M. Watson (UNAM), Simone Dichiara (GSFC/UMD), Alexander
Kutyrev (GSFC/UMD), William H. Lee (UNAM), Diego Gonzalez (UNAM), Margarita
Pereyra (UNAM), Srihari Ravi (ASU), and Eleonora Troja (GSFC/UMD) report:

We observed the field of the Fermi GBM GRB 210529B (Fermi Collaboration,
GCN Circ. 30101) with the DDOTI wide-field imager at the Observatorio
Astronómico Nacional on Sierra San Pedro Martir (
http://ddoti.astroscu.unam.mx) from 2021-05-30 03:35 to 11:19 UTC (3.7 to
11.4 hours after the trigger).

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: 230.01,
DEC: +36.34 (J2000 degrees). This region contains 6 instrumental fields or
about 400 square degrees. We obtained 58 minutes of exposure per
instrumental field in the w filter. We obtained AB photometry by
calibration against the APASS catalog.

We detect no likely candidates for the afterglow to our 10-sigma upper
limits of w = 20.25-20.58 (inter-quartile).

We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Martir.