TITLE:   GCN CIRCULAR
NUMBER:  28959
SUBJECT: GRB 201128A: DDOTI Observations 
DATE:    20/11/28 15:11:50 GMT
FROM:    Alan M Watson at UNAM  <alan@astro.unam.mx>

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

We observed the field of GRB 201128A (Lien et al., GCN Circ. 28958) with with
the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on
Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of
2020-11-28 UTC.

We observed from 2020-11-30 12:45 to 13:07 (from 6.3 to 6.7 hours after the
trigger) obtaining a total of 960 seconds exposure in the w filter. We calibrate
our images against the APASS catalog. Our 5-sigma limiting magnitude is w =
20.4.

Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogs, we
detect no uncatalogued sources in the Swift/XRT error region (Lien et al., GCN
Circ. 28958 to our 5-sigma limit.

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